Resin, resist composition and method for producing resist pattern

ABSTRACT

1. A resist composition includes (A1) a resin which includes a structural unit represented by formula (a4), and a structural unit having a sulfonyl group, and the resin has no acid-labile group, (A2) a resin having an acid-labile group, and an acid generator. 
     
       
         
         
             
             
         
       
     
     wherein R 3  represents a hydrogen atom or a methyl group, and R 4  represents a C 1  to C 24  saturated hydrocarbon group having a fluorine atom, and a methylene group contained in the saturated hydrocarbon group may be replaced by an oxygen atom or a carbonyl group.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Application No. 2014-187603filed on Sep. 16, 2014. The entire disclosures of Japanese ApplicationNo. 2014-187603 is incorporated hereinto by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosure relates to a resin, a resist composition and a method forproducing resist pattern.

2. Related Art

A resist composition including a resin having a combination ofstructural units below, a resin having an acid-labile group and an acidgenerator is described in Patent document of JP2014-41346A.

A resist composition including a resin having a combination ofstructural units below, a resin having an acid-labile group and an acidgenerator is described in Patent document of JP2010-204187A.

SUMMARY OF THE INVENTION

The disclosure provides following inventions of <1> to <15>.

<1> A Resist Composition Includes

(A1) a resin which includes a structural unit represented by formula(a4):

wherein R³ represents a hydrogen atom or a methyl group, and

R⁴ represents a C₁ to C₂₄ saturated hydrocarbon group having a fluorineatom, and a methylene group contained in the saturated hydrocarbon groupmay be replaced by

an oxygen atom or a carbonyl group, and

a structural unit having a sulfonyl group, and

the resin having no acid-labile group,

(A2) a resin having an acid-labile group, and

an acid generator.

<2> The resist composition according to <1>, wherein

the structural unit having a sulfonyl group is a structural unit havinga sultone ring.

<3> The resist composition according to <2>, wherein

the sultone ring is a ring represented by formula (T1):

wherein R⁸ represents a C₁ to C₁₂ alkyl group that may have a halogenatom or a hydroxy group, a halogen atom, a hydroxy group, a cyano group,a C₁ to C₁₂ alkoxy group, a C₆ to C₁₂ aryl group, a C₇ to C₁₈ aralkylgroup, a glycidyloxy group, a C₂ to C₁₂ alkoxycarbonyl group or a C₂ toC₄ acyl group, and

m represents an integer 0 to 9.

<4> The resist composition according to any one of <1> to <3>, wherein

the resin (A1) further includes a structural unit represented by formula(I):

the resin (A1) further includes a structural unit represented by formula(I):

wherein R¹ represents a hydrogen atom or a methyl group,

L¹ represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a methylene group may be replaced by an oxygenatom or a carbonyl group, and

-   -   R² represents a C₃ to C₁₈ alicyclic hydrocarbon group where a        hydrogen atom may be replaced by a C₁ to C₈ aliphatic        hydrocarbon group or a hydroxy group, provided that the carbon        atom directly bonded to L¹ has no aliphatic hydrocarbon group by        which a hydrogen atom has been replaced.

<5> The resist composition according to any one of <1> to <4>, wherein

R² is an unsubstituted C₃ to C₁₈ alicyclic hydrocarbon group.

<6> The resist composition according to any one of <1> to <5>, wherein

the structural unit represented by the formula (a4) is at least onestructural unit selected from the group consisting of a structural unitrepresented by formula (a4-0), a structural unit represented by formula(a4-1), a structural unit represented by formula (a4-2) and a structuralunit represented by formula (a4-3):

wherein R^(f1) represents a hydrogen atom or a methyl group, and

R^(f2) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f3) represents a hydrogen atom or a methyl group,

L³ represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and

R^(f4) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f5) represents a hydrogen atom or a methyl group,

L⁴ represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and

R^(f6) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f7) represents a hydrogen atom or a methyl group,

L⁵ represent a C₁ to C₆ alkanediyl group,

A^(f13) represents a C₁ to C₁₈ divalent saturated hydrocarbon group thatmay have a fluorine atom,

x^(f12) represents an oxycarbonyl group or a carbonyloxy group, and

A^(f14) represents a C₁ to C₁₇ saturated hydrocarbon group that may havea fluorine atom,

provided that at least one of A^(f13) and A^(f14) represents a saturatedhydrocarbon group having a fluorine atom.

<7> The resist composition according to any one of <1> to <6>, wherein

the resin (A2) includes a structural unit selected from the groupconsisting of a structural unit represented by formula (a1-1) and astructural unit represented by formula (a1-2):

wherein L^(a1) and L^(a2) independently represent —O— or*—O—(CH₂)_(k1)—CO—O—,

k1 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a4) and R^(a5) each independently represent a hydrogen atom or amethyl group,

R^(a6) and R^(a7) each independently represent a C₁ to C₈ alkyl group, aC₃ to C₁₈ alicyclic hydrocarbon group or a combination thereof,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.

<8> The resist composition according to any one of <1> to <7>, wherein

the resin (A2) includes a structural unit represented by formula (a1-1)and a structural unit represented by formula (a1-2).

<9> A method for producing a resist pattern including steps (1) to (5);

(1) applying the resist composition according to any one of <1> to <8>onto a substrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer, and

(5) developing the heated composition layer.

<10> A resin includes

a structural unit represented by formula (a4) and

wherein R³ represents a hydrogen atom or a methyl group,

R⁴ represents a C₁ to C₂₄ saturated hydrocarbon group having a fluorineatom and a methylene group contained in the saturated hydrocarbon groupmay be replaced by an oxygen atom or a carbonyl group and

a structural unit having a sulfonyl group,

the resin has no acid-labile group.

<11> The resin according to <10>, wherein

the structural unit having a sulfonyl group is a structural unit havinga sultone ring.

<12> The resin according to <11>, wherein

the sultone ring is a ring represented by formula (T1):

wherein R⁸ represents a C₁ to C₁₂ alkyl group that may have a halogenatom or a hydroxy group, a halogen atom, a hydroxy group, a cyano group,a C₁ to C₁₂ alkoxy group, a C₆ to C₁₂ aryl group, a C₇ to C₁₈ aralkylgroup, a glycidyloxy group, a C₂ to C₁₂ alkoxycarbonyl group or a C₂ toC₄ acyl group, and

m represents an integer 0 to 9.

<13> The resin according to any one of <10> to <12>,

wherein the resin (A1) further includes a structural unit represented byformula (I):

wherein R¹ represents a hydrogen atom or a methyl group,

L¹ represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a methylene group may be replaced by an oxygenatom or a carbonyl group, and

R² represents a C₃ to C₁₈ alicyclic hydrocarbon group where a hydrogenatom may be replaced by a C₁ to C₈ aliphatic hydrocarbon group or ahydroxy group, provided that the carbon atom directly bonded to L¹ hasno aliphatic hydrocarbon group by which a hydrogen atom has beenreplaced.

<14> The resin according to any one of <10> to <13>, wherein

R² is an unsubstituted C₃ to C₁₈ alicyclic hydrocarbon group.

<15> The resin according to any one of <10> to <14>, wherein

the structural unit represented by the formula (a4) is at least onestructural unit selected from the group consisting of a structural unitrepresented by formula (a4-0), a structural unit represented by formula(a4-1), a structural unit represented by formula (a4-2) and a structuralunit represented by formula (a4-3):

wherein R^(f1) represents a hydrogen atom or a methyl group, and

R^(f2) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f3) represents a hydrogen atom or a methyl group,

L³ represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and

R^(f4) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f5) represents a hydrogen atom or a methyl group,

L⁴ represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and

R^(f6) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f7) represents a hydrogen atom or a methyl group,

L⁵ represent a C₁ to C₆ alkanediyl group,

A^(f13) represents a C₁ to C₁₈ divalent saturated hydrocarbon group thatmay have a fluorine atom,

X^(f12) represents an oxycarbonyl group or a carbonyloxy group, and

A^(f14) represents a C₁ to C₁₇ saturated hydrocarbon group that may havea fluorine atom,

provided that at least one of A^(f13) and A^(f14) represents a saturatedhydrocarbon group having a fluorine atom.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

“(Meth)acrylic monomer” means a monomer having a structure of“CH₂═CH—CO—” or “CH₂═C(CH₃)—CO—”, as well as “(meth)acrylate” and“(meth)acrylic acid” mean “an acrylate or methacrylate” and “an acrylicacid or methacrylic acid,” respectively. Herein, chain structure groupsinclude those having a linear structure and those having a branchedstructure. The indefinite articles “a” and “an” are taken as the samemeaning as “one or more”.

In the specification, the term “solid components” means components otherthan solvents in a resist composition.

<Resin>

The resin of the disclosure, which resin is sometimes referred to as“resin (A1)”, includes a structural unit represented by formula (a4) asdescribed later and a structural unit having a sulfonyl [SO₂] group, andthe resin has no acid-labile group.

The resin (A1) is useful for resist compositions such as those of thedisclosure.

The resin (A1) may further include a structural unit represented byformula (I) as described later.

The resin (A1) preferably consists of the structural unit represented byformula (a4), and a structural unit having a sulfonyl group, or consistsof the structural unit represented by formula (a4), a structural unithaving a sulfonyl group, and a structural unit represented by formula(I).

<Resist Composition>

The resist composition of the disclosure includes

resin (A1)

a resin which has an acid-labile group (which is sometimes referred toas “resin (A2)”), and

an acid generator.

Here the “acid-labile group” means a group having a leaving groupcapable of detaching by contacting with an acid to thereby form ahydrophilic group such as a hydroxy or carboxy group.

The resist composition preferably includes a quencher (which issometimes referred to as “quencher (C)”) and/or a solvent (which issometimes referred to as “solvent (E)”) in addition to the resins (A1)and (A2), and the acid generator. Further, the resist composition mayinclude a resin other than the resins (A1) and (A2) (which is sometimesreferred to as “resin (X)”).

<Resin (A1)>

The resin (A1) includes a structural unit represented by formula (a4)(which is sometimes referred to as “structural unit (a4)”):

wherein R³ represents a hydrogen atom or a methyl group, and

R⁴ represents a C₁ to C₂₄ saturated hydrocarbon group having a fluorineatom, and a methylene group contained in the saturated hydrocarbon groupmay be replaced by an oxygen atom or a carbonyl group.

Examples of the saturated hydrocarbon group having a fluorine atom of R⁴include a fluorinated alkyl group such as difluoromethyl,trifluoromethyl, 1,1-difluoroethyl, 2,2-difluoroethyl,2,2,2-trifluoroethyl, perfluoroethyl, 1,1,2,2-tetrafluoropropyl,1,1,2,2,3,3-hexafluoropropyl, perfluoroethylmethyl,1-(trifluoromethyl)-1,2,2,2-tetrafluoroethyl,1-(trifluoromethyl)-2,2,2-trifluoroethyl, perfluoropropyl,1,1,2,2-tetrafluorobutyl, 1,1,2,2,3,3-hexafluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, perfluorobutyl,1,1-bis(trifluoromethyl)methyl-2,2,2-trifluoroethyl,2-(perfluoropropyl)ethyl, 1,1,2,2,3,3,4,4-octafluoropentyl,perfluoropentyl, 1, 1,2,2,3,3,4,4,5,5-decafluoroentyl,1,1-bis(trifluoromethyl)2,2,3,3,3-pentafluoropropyl,2-(perfluorobutyl)ethyl, 1,1,2,2,3,3,4,4,5,5-decafluorohexyl,1,1,2,2,3,3,4,4,5,5,6,6-dodecafluorohexyl, perfluoropentylmethyl andperfluorohexyl groups; and

a fluorinated cycloalkyl group such as perfluorocyclohexyl andperfluoroadamantyl groups.

The structural unit (a4) is preferably a structural unit represented byformula (a4-0), a structural unit represented by formula (a4-1), astructural unit represented by formula (a4-2), and a structural unitrepresented by formula (a4-3) described later, more preferably thestructural unit represented by formula (a4-0), the structural unitrepresented by formula (a4-1) and the structural unit represented byformula (a4-2), still more preferably the structural unit represented byformula (a4-0).

Hereinafter, the structural unit represented by formula (a4-0), thestructural unit represented by formula (a4-1), the structural unitrepresented by formula (a4-2), and the structural unit represented byformula (a4-3) are sometimes referred to as “the structural unit (a4-0),“the structural unit (a4-1)”, “the structural unit (a4-2)”, and “thestructural unit (a4-3)”, respectively.

In the formula (a4-0), R^(f1) represents a hydrogen atom or a methylgroup, and

R^(f2) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom.

In the formula (a4-1), R^(f3) represents a hydrogen atom or a methylgroup,

L³ represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and

R^(f4) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom.

The total carbon number contained in the group of L³ and R^(f4) ispreferably 21 or less. The total carbon number of the group includes thenumber of the carbon atom replaced by an oxygen atom or a carbonylgroup.

In the formula (a4-2), R^(f5) represents a hydrogen atom or a methylgroup,

L⁴ represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and

R^(f6) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom.

The total carbon number contained in the group of L⁴ and R^(f6) ispreferably 21 or less.

In the formula (a4-1) and the formula (a4-2), examples of the divalentsaturated hydrocarbon group of L³ and L⁴ include a saturated aliphatichydrocarbon group and a saturated alicyclic hydrocarbon group, and asaturated aliphatic hydrocarbon group is preferred.

Examples of the saturated aliphatic hydrocarbon group include analkanediyl such as methylene, ethylene, propanediyl, butanediyl andpentanediyl.

Examples of the saturated alicyclic hydrocarbon group include any of amonocyclic group and a polycyclic group. Examples of the monocyclicgroup include cycloalkanediyl group such as cyclopentanediyl andcyclohexanediyl groups. Examples of the polycyclic group includeadamantanediyl and norbornanediyl groups.

Examples of the saturated hydrocarbon group in which a methylene grouphas been replaced by an oxygen atom or a carbonyl group include groupsrepresented by formula (L3-1) to formula (L3-3). In the formula (L3-1)to the formula (L3-3), * represents a binding site to an oxygen atom.

In the formulae, X₃ ^(X1) represents an oxycarbonyl group or acarbonyloxy group,

L₃ ^(X1) represents a C₁ to C₁₆ divalent saturated aliphatic hydrocarbongroup,

L₃ ^(X2) represents a single bond or a C₁ to C₁₅ divalent saturatedaliphatic hydrocarbon group,

provided that the total carbon number contained in the group of L₃ ^(X1)and L₃ ^(X2) is 16 or less;

L₃ ^(X3) represents a single bond or a C₁ to C₁₇ divalent saturatedaliphatic hydrocarbon group,

L₃ ^(X4) represents a single bond or a C₁ to C₁₆ divalent saturatedaliphatic hydrocarbon group,

provided that the total carbon number contained in the group of L₃ ^(X3)and L₃ ^(X4) is 17 or less;

L₃ ^(X5) represents a C₁ to C₁₅ divalent saturated aliphatic hydrocarbongroup,

L₃ ^(X6) and L₃ ^(X7) each independently represent a single bond or a C₁to C₁₄ divalent saturated aliphatic hydrocarbon group,

provided that the total carbon number contained in the group of L₃^(X5), L₃ ^(X6) and L₃ ^(X7) is 15 or less.

L₃ ^(X1) is preferably a C₁ to C₈ divalent saturated aliphatichydrocarbon group, and more preferably methylene or ethylene group.

L₃ ^(X2) is preferably a C₁ to C₈ divalent saturated aliphatichydrocarbon group, and more preferably methylene or ethylene group.

L₃ ^(X3) is preferably a C₁ to C₈ divalent saturated aliphatichydrocarbon group.

L₃ ^(X4) is preferably a C₁ to C₈ divalent saturated aliphatichydrocarbon group.

L₃ ^(X5) is preferably a C₁ to C₈ divalent saturated aliphatichydrocarbon group, and more preferably methylene or ethylene group.

L₃ ^(X6) is preferably a C₁ to C₈ divalent saturated aliphatichydrocarbon group, and more preferably methylene or ethylene group.

L₃ ^(X7) is preferably a C₁ to C₈ divalent saturated aliphatichydrocarbon group.

Examples of the group represented by the formula (L3-1) include thefollowing ones.

Examples of the group represented by the formula (L3-2) include thefollowing ones.

Examples of the group represented by the formula (L3-3) include thefollowing ones.

L³ and L⁴ are preferably methylene group or ethylene group.

Examples of the saturated hydrocarbon group having a fluorine atominclude the same examples as those referring to the group of R⁴ in theformula (a4).

Examples of the structural unit (a4-0) include the following ones.

Examples of the structural unit (a4-0) include those in which a methylgroup corresponding to R^(f1) has been replaced by a hydrogen atom inthe structural units represented by the above formulae.

Examples of the structural unit (a4-1) include the following ones.

Examples of the structural unit (a4-1) include those in which a methylgroup corresponding to R^(f3) has been replaced by a hydrogen atom inthe structural units represented by the above formulae.

Examples of the structural unit (a4-2) include the following ones.

Examples of the structural unit (a4-2) include those in which a methylgroup corresponding to R^(f5) has been replaced by a hydrogen atom inthe structural units represented by the above formulae.

Examples of the structural unit (a4) include a structural unit presentedby the formula (a4-3) (which is sometimes referred to as “structuralunit (a4-3)”):

wherein R^(f7) represents a hydrogen atom or a methyl group,

L⁵ represent a C₁ to C₆ alkanediyl group,

A^(f13) represents a C₁ to C₁₈ divalent saturated hydrocarbon group thatmay have a fluorine atom,

X^(f12) represents an oxycarbonyl group or a carbonyloxy group, and

A^(f14) represents a C₁ to C₁₇ saturated hydrocarbon group that may havea fluorine atom,

provided that at least one of A^(f13) and A^(f14) represents a saturatedhydrocarbon group having a fluorine atom.

In the formula (a4-3), the total carbon number contained in the group ofL⁵, A^(f13) and A^(f14) is preferably 20 or less.

Examples of the alkanediyl group of L⁵ include a chain alkanediyl groupsuch as methylene, ethylene, propane-1,3-diyl, butane-1,4-diyl,pentane-1,5-diyl and hexane-1,6-diyl groups;

a branched alkanediyl group such as 1-methylpropane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl,1-methylbutane-1,4-diyl and 2-methylbutane-1,4-diyl groups.

Examples of the divalent saturated hydrocarbon group of A^(f13) includeany of a saturated aliphatic hydrocarbon group, a saturated alicyclichydrocarbon group, or a combination thereof. The aliphatic hydrocarbongroup may have a carbon-carbon unsaturated bond, and is preferably asaturated aliphatic hydrocarbon group.

The saturated hydrocarbon group that may have a fluorine atom of A^(f13)is preferably the saturated aliphatic hydrocarbon group that may have afluorine atom, and preferably a perfuloroalkandiyl group.

Examples of the divalent saturated aliphatic hydrocarbon that may have afluorine atom include an alkanediyl group such as methylene, ethylene,propanediyl, butanediyl and pentanediyl groups; a perfluoroalkanediylgroup such as difluoromethylene, perfluoroethylene,perfluoropropanediyl, perfluorobutanediyl and perfluoropentanediylgroups.

The divalent saturated alicyclic hydrocarbon group that may have afluorine atom is any of a monocyclic or a polycyclic group.

Examples of the monocyclic group include cyclohexanediyl andperfluorocyclohexanediyl groups.

Examples of the polycyclic group include adamantanediyl, norbornanediyl,and pertluoroadamantanediyl groups.

Examples of the saturated hydrocarbon group of A^(f14) include any of asaturated aliphatic hydrocarbon group, a saturated alicyclic hydrocarbongroup, or a combination thereof. The aliphatic hydrocarbon group mayhave a carbon-carbon unsaturated bond, and is preferably a saturatedaliphatic hydrocarbon group.

Examples of the saturated aliphatic hydrocarbon group that may have ahalogen atom include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, pentyl, hexyl, perfluorohexyl,hepthyl, perfluoroheptyl, octyl and perfluorooctyl groups.

The saturated cyclic aliphatic hydrocarbon group that may have afluorine atom is any of monocyclic or polycyclic group. Examples of themonocyclic group include cyclopropylmethyl, cyclopropyl,cyclobutylmethyl, cyclopentyl, cyclohexyl and perfluorocyclohexylgroups. Examples of the polycyclic group include adamantyl, norbornyland perfluoroadamantyl groups

Examples of the combination of the saturated aliphatic hydrocarbon groupand saturated alicyclic hydrocarbon group include adamantylmethyl,norbornylmethyl, and perfluoroadamantylmethyl groups

In the formula (a4-3), L⁵ is preferably an ethylene group.

The saturated aliphatic hydrocarbon group of A^(f13) is preferably a C₁to C₆ aliphatic hydrocarbon group, more preferably a C₂ to C₃ aliphatichydrocarbon group.

The saturated hydrocarbon group of A^(f14) is preferably a C₃ to C₁₂saturated hydrocarbon group, more preferably a C₃ to C₁₀ hydrocarbongroup. Among these, A^(f14) is preferably a group containing a C₃ to C₁₂alicyclic hydrocarbon group, more preferably a cyclopropylmethyl,cyclopentyl, cyclohexyl, norbornyl or adamantyl group.

Examples of the structural unit (a4-3) include the following ones.

Examples of the structural unit (a4-3) include those in which a methylgroup corresponding to R^(f7) has been replaced by a hydrogen atom inthe structural units represented by the above formulae.

The structural unit (a4-0) is derived from a compound represented byformula (a4′-0) (which is sometimes referred to as “compound (a4′-0)”):

wherein R^(f1) and R^(f2) are as defined above.

As the compound (a4′-0), a marketed product or a compound which isproduced by a known method may be used.

The known method includes a method in which (meth)acrylic acid orderivatives thereof, for example, (meth)acrylic chloride is condensedwith a suitable alcohol (HO—R^(f2)). The marketed product is thefollowing ones.

The structural unit (a4-1) is derived from a compound represented byformula (a4′-1) (which is sometimes referred to as “compound (a4′-1)”):

wherein R^(f3), R^(f4) and L³ are as defined above.

The compound (a4′-1) can be produced by reacting a compound representedby formula (a4′-1-1) with a compound represented by formula (a4′-1-2) inthe presence of a basic catalyst in a solvent:

wherein R^(f3), R^(f4) and L³ are as defined above.

Preferred examples of the solvent include tetrahydrofuran.

Preferred examples of the basic catalyst include pyridine.

Examples of the compound represented by the formula (a4′-1-1) includehydroxyethylmethacrylate, which is available on the market. Also, acompound which is produced by a known method including a method in which(meth)acrylic acid or derivatives thereof, for example, (meth)acrylicchloride is condensed with a suitable diol (HO-L³-OH), can be used.

As the compound represented by the formula (a4′-1-2), an anhydrate thathas been converted from an appropriate caroboxylic acid in accordancewith R^(f4) can be used. Examples of the marketed product includeheptafluorobutyric anhydride.

The structural unit (a4-2) is derived from a compound represented byformula (a4′-2) (which is sometimes referred to as “compound (a4′-2)”):

wherein R^(f5), R^(f6) and L⁴ are as defined above.

The compound (a4′-2) can be produced by reacting a compound representedby formula (a4′-2-1) with a compound represented by formula (a4′-2-2) inthe presence of a catalyst in a solvent:

wherein R^(f6), R³ and L⁴ are as defined above.

Preferred examples of the solvent include dimethylformamide.

Preferred examples of the catalyst include potassium carbonate andpotassium iodide.

Preferred examples of the compound represented by the formula (a4′-2-1)include a methacrylic acid, which is available on the market.

The compound represented by the formula (a4′-2-2) can be produced byreacting a compound represented by formula (a4′-2-3) with a compoundrepresented by formula (a4′-2-4) in the presence of a basic catalyst ina solvent:

wherein R^(f6) and L⁴ are as defined above.

Preferred examples of the solvent include tetrahydrofuran.

Preferred examples of the basic catalyst include pyridine.

As the compound represented by the formula (a4′-2-3), a compound inaccordance with R^(f4) can be used. When chloroacetyl chloride is usedas the compound represented by the formula (a4′-2-3), a compoundrepresented by the formula (a4′-2-2) in which L⁴ is methyl group can beproduced. Chloroacetyl chloride is available on the market.

As the compound represented by the formula (a4′-2-4), an alcohol inaccordance with R^(f6) can be used. When2,2,3,3,4,4,4-heptafluoro-1-butanol is used as the compound representedby the formula (a4′-2-4), a compound represented by the formula(a4′-2-2) in which R^(f6) is an aliphatic hydrocarbon group has beensubstituted with fluorine atom can be produced.2,2,3,3,4,4,4-Heptafluoro-1-butanol is available on the market.

The structural unit (a4-3) is derived from a compound represented byformula (a4′-3) (which is sometimes referred to as “compound (a4′-3)”):

wherein R^(f7), L⁵, A^(f13), X^(f12) and A^(f14) are as defined above.

The compound represented by the formula (a4′-3) can be produced byreacting a compound represented by the formula (a4′-3-1) with acarboxylic acid represented by the formula (a4′-3-2). This reaction isgenerally carried out in a solvent:

wherein R^(f7), L⁵, A^(f13), X^(f12) and A^(f14) are as defined above.

Preferred examples of the solvent include tetrahydrofuran and toluene.

As the compound represented by the formula (a4′-3-1), a marketed productor a compound which is produced by a known method may be used.

The known method includes a method in which (meth)acrylic acid orderivatives thereof, for example, (meth)acrylic chloride is condensedwith a suitable diol (HO-L⁵-OH). Examples of the marketed productinclude hydroxyethyl methacrylate.

The compound represented by the formula (a4′-3-2) can be produced by aknown method. Examples thereof include the following ones.

The resin (A1) includes a structural unit having an SO₂ group.

The structural unit having an SO₂ group preferably has an SO₂ group in aside chain of the structural unit.

The structural unit having an SO₂ group may have a liner structurehaving an SO₂ group, a branched structure having an SO₂ group or acyclic structure having an SO₂ group. The structural unit has preferablya cyclic structure having an SO₂ group, and more preferably a sultonering.

Examples of the sultone ring include rings represented by formula(T¹-1), formula (T¹-2), formula (T¹-3), and formula (T¹-4). The sultonering is any one of monocyclic or polycyclic one. The polycyclic sultonemeans a bridged ring including atomic group constituting the ring of—SO₂—O—, and example thereof include the ring represented by formula(T¹-1) or formula (T¹-2). The sultone ring may include further a heteroatom other than —SO₂—O—, such as the ring represented by formula (T¹-2).Examples of the hetero atom include an oxygen atom, a sulfur atom and anitrogen atom. An oxygen atom is preferred.

The sultone ring may have a substituent. Examples thereof include a C₁to C₁₂ alkyl group that may have a halogen atom or a hydroxy group, ahalogen atom, a hydroxy group, a cyano group, a C₁ to C₁₂ alkoxy group,a C₆ to C₁₂ aryl group, a C₇ to C₁₈ aralkyl group, a glycidyloxy group,a C₂ to C₁₂ alkoxycarbonyl and a C₂ to C₄ acyl group.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of the alkyl group include methyl, ethyl, propyl, butyl,pentyl, hexyl, octyl and decyl groups. A C₁ to C₆ alkyl group ispreferred, and a methyl group and an ethyl group are more preferred.

Examples of the alkyl group having a halogen atom includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, tricloromethyl, tribromomethyl andtriiodomethyl groups. Trifluoromethyl group is preferred.

Examples of the alkyl group having a hydroxy group include hydroxymethyland 2-hydroxyethyl groups.

Examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, octyloxy, decyloxy and dodecyooxy groups.

Examples of the aryl group include phenyl, naphthyl, anthryl,p-methylphenyl, p-tert-butylphenyl, p-adamantylphenyl, tolyl, xylyl,cumenyl, mesityl, biphenyl, phenanthryl, 2,6-diethylphenyl and2-methyl-6-ethylphenyl groups.

Examples of the aralkyl group include benzyl, phenethyl, phenylpropyl,naphthylmethyl and naphthylethyl groups.

Examples of the alkoxycarbonyl group include a group in which a carbonylgroup is bonds to the alkoxy group, such as methoxycarbonyl andethoxycarbonyl groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

In terms of an easy manufacturing of a monomer having a SO₂ group, anunsubstituted sultone ring is preferred.

The sultone ring is preferably a ring represented by formula (T1′):

wherein X^(1I) represents an oxygen atom, a sulfur atom or a methylenegroup,

R⁴¹ represents a C₁ to C₁₂ alkyl group that may have a halogen atom or ahydroxy group, a halogen atom, a hydroxy group, a cyano group, a C₁ toC₁₂ alkoxy group, a C₆ to C₁₂ aryl group, a C₇ to C₁₈ aralkyl group, aglycidyloxy group, a C₂ to C₁₂ alkoxycarbonyl or a C₂ to C₄ acyl group,and

ma represents an integer 0 to 9.

X¹¹ is preferably an oxygen atom or a methylene group, and morepreferably an oxygen atom.

R⁴¹ is preferably a C₁ to C₁₂ alkyl group that may have a halogen atomor a hydroxy group.

The sultone ring is more preferably a ring represented by formula (T1):

wherein R⁸ represents a C₁ to C₁₂ alkyl group that may have a halogenatom or a hydroxy group, a halogen atom, a hydroxy group, a cyano group,a C₁ to C₁₂ alkoxy group, a C₆ to C₁₂ aryl group, a C₇ to C₁₈ aralkylgroup, a glycidyloxy group, a C₂ to C₁₂ alkoxycarbonyl group or a C₂ toC₄ acyl group, and m represents an integer 0 to 9.

“ma” in the formula (T1′) and “m” in the formula (T1) are preferably 0or 1 and more preferably 0.

Example of the structure having an SO₂ group include the following ones.

The structural unit having an SO₂ group has preferably the followingrings. In each of the following formulae, * represents a bonding site.

The structural unit having an SO₂ group generally has a main chainderived from a polymerizable group. Examples of the polymerizable groupinclude a vinyl group, an acryloyl group, a methacryloyl group, anacryloyloxy group, a methacryloyloxy group, an acryloylamino group and amethacryloylamino group, and preferably a vinyl group, an acryloyl groupand a methacryloyl group.

The structural unit having an SO₂ group may have a structure representedby formula (a6-1):

wherein R⁵ represents a C₁ to C₆ alkyl group that may have a halogenatom, a hydrogen atom or a halogen atom,

A⁴ represents a sulfur atom, an oxygen atom or an NH group,

A⁵ represents a single bond or a C₁ to C₁₆ alkanediyl group where amethylene group may be replaced by an oxygen atom, a carbonyl group oran NH group, and

* represents a binding site to a group having an SO₂ group.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of the alkyl group of R⁵ include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups.For R⁵, C₁ to C₄ alkyl groups are preferred, and a methyl and an ethylgroup are more preferred.

For R⁵, examples of the alkyl group having a halogen atom includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, trichloromethyl, tribromomethyl andtriiodomethyl groups.

R⁵ is preferably a hydrogen atom or a C₁ to C₄ alkyl group, morepreferably a hydrogen atom, a methyl group or an ethyl group, and stillmore preferably a hydrogen atom or a methyl group.

Examples of the alkanediyl group of A⁵ include methylene, ethylene,propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl, pentane-1,5-diyl,hexane-1,6-diyl, butane-1,3-diyl, 2-methylpropane-1,3-diyl,2-methylpropane-1,2-diyl, pentane-1,4-diyl and 2-methylbutane-1,4-diylgroups.

As to the alkanediyl group of A⁵, examples of a group in which amethylene group has been replaced by the oxygen atom, a carbonyl groupor an NH group include -A²-O*, -A²-CO—O*, -A²-O—CO—*, -A²-NH—CO—O—*,-A²-CO—O-A³-CO—O* and -A²-O—CO-A³-O*.

A² and A³ each independently represent a C₁ to C₆ alkanediyl group.

Examples of the alkanediyl group of A² and A³ include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl andn-hexyl groups.

A⁴ is preferably an oxygen atom.

A⁵ is preferably a single bond or -A²-CO—O—*, and more preferably asingle bond, —CH₂—CO—O; or —C₂H₄—CO—O—*.

Examples of the structures inducing the structure presented by theformula (a6-1) include the following ones. In each of the formulae, *represents a binding site to a group having a SO₂ group and t representsan integer of 1 to 6.

The structural unit having an SO₂ group is preferably derived from acompound represented by formula (a6′):

wherein R⁵ represents a C₁ to C₆ alkyl group that may have a halogenatom, a hydrogen atom or a halogen atom,

A⁴ represents a sulfur atom, an oxygen atom or an NH group, and

A⁵ represents a single bond or a C₁ to C₁₆ alkanediyl group where amethylene group may be replaced by an oxygen atom, a carbonyl group oran NH group.

The structural unit derived from the compound represented by the formula(a6′) is preferably one represented by formula (a6):

wherein R⁵ represents a C₁ to C₆ alkyl group that may have a halogenatom, a hydrogen atom or a halogen atom,

A¹ represents a single bond -A²-O—*, -A²-CO—O—*, -A²-CO—O-A³-CO—O—* or-A²-O—CO-A³-O—*,

* represents a binding site to a sultone ring, and

A² and A³ each independently represent a C₁ to C₆ alkanediyl group.

A¹ is preferably a single bond or -A²-CO—O—*, and more preferably asingle bond, —CH₂ or —C₂H₄—CO—O—*.

Examples of the structural unit having an SO₂ group preferably includethe following ones.

A compound from which the structural unit having an SO₂ group is derivedcan be produced by a known method.

The proportion of the structural unit (a4) is preferably 20 to 97% bymole, preferably 25 to 95% by mole, more preferably 30 to 90% by mole,with respect to the total structural units (100% by mole) of the resin(A1).

The proportion of the structural unit having an SO₂ group is preferably3 to 80% by mole, more preferably 5 to 75% by mole, still morepreferably 5 to 70% by mole, with respect to the total structural units(100% by mole) of the resin (A1).

When the proportions of the structural unit (a4) and the structural unithaving an SO₂ group are within the above ranges, resist patterns withexcellent DOF and reduced defects can be produced.

The resin (A1) can be produced by a known polymerization method, forexample, radical polymerization method, using one or more species ofmonomers inducing the structural units as described above, such as themonomer (a4′-0), the monomer (a4′-1), the monomer (a4′-2), the monomer(a4′-3) and the monomer (a6′), and optionally one or more of a monomerrepresented by formula (I′) and/or other monomers having no acid-labilegroup, as described below. The proportion of the structural unit in theresin (A1) can be adjusted by changing the amount of a monomer used inpolymerization.

The resin (A1) preferably further include a structural unit representedby formula (I) which is different from the structural unit (a2)described below (which is sometimes referred to as “structural unit(I)”).

In the formula, R¹ represents a hydrogen atom or a methyl group,

L¹ represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a methylene group may be replaced by an oxygenatom or a carbonyl group, and

R² represents a C₃ to C₁₈ alicyclic hydrocarbon group where a hydrogenatom may be replaced by a C₁ to C₈ aliphatic hydrocarbon group or ahydroxy group, provided that the carbon atom directly bonded to L¹ hasno aliphatic hydrocarbon group by which a hydrogen atom has beenreplaced.

A methylene group contained in the saturated hydrocarbon group of L¹ maybe replaced by an oxygen atom, and an ethylene group contained in thesaturated hydrocarbon group of L¹ may be replaced by an ester group.

Examples of the alicyclic hydrocarbon group of R² include any one of amonocyclic group or a polycyclic group. Examples of the monocyclicalicyclic hydrocarbon group include cyclopropyl, cyclobutyl, cyclopentyland cyclohexyl groups. Examples of the polycyclic hydrocarbon groupinclude adamantyl and norbornyl groups.

Examples of the C₁ to C₈ aliphatic hydrocarbon group include an alkylgroup such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl,tert-butyl, n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octylgroups.

Examples of the alicyclic hydrocarbon group having a substituent of R²include 3-hydroxyadamantyl group and 3-methyladamantyl group.

R² is preferably an unsubstituted C₃ to C₁₈ alicyclic hydrocarbon group,and more preferably an adamantyl, norbornyl or cyclohexyl group.

Examples of the divalent saturated hydrocarbon group of L¹ include asaturated aliphatic hydrocarbon group and a saturated alicyclichydrocarbon group, and a saturated aliphatic hydrocarbon group ispreferred.

Examples of the saturated aliphatic hydrocarbon group include analkanediyl such as methylene, ethylene, propanediyl, butanediyl andpentanediyl.

Examples of the saturated alicyclic hydrocarbon group include any of amonocyclic group and a polycyclic group. Examples of the monocyclicgroup include cycloalkanediyl group such as cyclopentanediyl andcyclohexanediyl groups. Examples of the polycyclic group includeadamantanediyl and norbornanediyl groups.

Examples of the saturated hydrocarbon group in which a methylene grouphas been replaced by an oxygen atom or a carbonyl group include groupsrepresented by the formula (L1-1) to the formula (L1-4). In the formula(L1-1) to the formula (L1-4), * represents a binding site to an oxygenatom.

In the formulae, X^(X1) represents an oxycarbonyl group or a carbonyloxygroup,

L^(X1) represents a C₁ to C₁₆ divalent saturated aliphatic hydrocarbongroup,

L^(X2) represents a single bond or a C₁ to C₁₅ divalent saturatedaliphatic hydrocarbon group, provided that the total carbon numbercontained in the groups of L^(X1) and L^(X2) is 16 or less;

L^(X3) represents a single bond or a C₁ to C₁₇ divalent saturatedaliphatic hydrocarbon group,

L^(X4) represents a single bond or a C₁ to C₁₆ divalent saturatedaliphatic hydrocarbon group,

provided that the total carbon number contained in the groups of L^(X3)and L^(X4) is 17 or less;

L^(X5) represents a C₁ to C₁₅ divalent saturated aliphatic hydrocarbongroup,

L^(X6) and L^(X7) each independently represent a single bond or a C₁ toC₁₄ divalent saturated aliphatic hydrocarbon group,

provided that the total carbon number contained in the groups of L^(X5),L^(X6) and L^(X7) is 15 or less;

L^(X8) and L^(X9) each independently represent a single bond or a C₁ toC₁₂ divalent saturated aliphatic hydrocarbon group,

W^(X1) represents a C₃ to C₁₅ divalent saturated alicyclic hydrocarbongroup,

provided that the total carbon number contained in the groups of L^(X8),L^(X9) and W^(X1) is 15 or less.

L^(X1) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably a methylene or ethylene group.

L^(X2) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond.

L^(X3) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup.

L^(X4) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X5) is preferably a C₁ to C₈ divalent saturated aliphatic hydrocarbongroup, and more preferably methylene or ethylene group.

L^(X6) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably methylene or ethylenegroup.

L^(X7) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group.

L^(X8) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond or amethylene group.

L^(X9) is preferably a single bond or a C₁ to C₈ divalent saturatedaliphatic hydrocarbon group, and more preferably a single bond ormethylene group.

W^(X1) is preferably a C₃ to C₁₀ divalent saturated alicyclichydrocarbon group, and more preferably a cyclohexanediyl oradamantanediyl group.

Examples of the group represented by the formula (L1-1) include thefollowing ones.

Examples of the group represented by the formula (L1-2) include thefollowing ones.

Examples of the group represented by the formula (L1-3) include thefollowing ones.

Examples of the group represented by the formula (L1-4) include thefollowing ones.

L¹ is preferably a single bond or the groups represented by the formula(L1-1).

Examples of the structural unit (I) include the following ones.

Examples of the structural unit (I) include those in which a methylgroup corresponding to R¹ has been replaced by a hydrogen atom in thestructural units represented by the above formulae.

The structural unit (I) is derived from a compound represented byformula (I′) (which is sometimes referred to as “compound (I′)”):

wherein R¹, L¹ and R² are as defined above.

As the compound (I′), a marketed product or a compound which is producedby a known method may be used.

The known method includes a method in which (meth)acrylic acid orderivatives thereof, for example, (meth)acrylic chloride is condensedwith a suitable alcohol (HO-L¹-R²). Examples of the marketed productinclude adamantane-1-yl methacrylate and adamantane-1-yl acrylate.

When the resin (A1) includes the structural unit (I), the proportion ofthe structural unit (a4) is preferably 20 to 80% by mole, morepreferably 25 to 70% by mole, still more preferably 30 to 60% by mole,with respect to the total structural units (100% by mole) of the resin(A1).

When the resin (A1) includes the structural unit (I), the proportion ofthe structural unit having an SO₂ group is preferably 3 to 50% by mole,more preferably 5 to 40% by mole, still more preferably 5 to 30% bymole, with respect to the total structural units (100% by mole) of theresin (A1).

When the resin (A1) includes the structural unit (1), the proportion ofthe structural unit (I) is preferably 17 to 77% by mole, more preferably25 to 70% by mole, still more preferably 35 to 65% by mole, with respectto the total structural units (100% by mole) of the resin (A).

When the proportions of the structural unit (a4), the structural unithaving an SO₂ group and the structural unit (I) are within the aboveranges, resist patterns with excellent DOF and reduced defects can beproduced.

The resin (A1) may further include a structural unit (a2) and/or astructural unit (a3) described below.

The weight average molecular weight of the resin (A1) is preferably5,000 or more (more preferably 7,000 or more, and still more preferably10,000 or more), and 80,000 or less (more preferably 50,000 or less, andstill more preferably 30,000 or less).

In the present specification, the weight average molecular weight is avalue determined by gel permeation chromatography using polystyrene asthe standard product. The detailed condition of this analysis isdescribed in Examples.

<Resin (A2)>

The resin (A2) includes a structural unit having an acid-labile group(which is sometimes referred to as “structural unit (a1)”). Also, theresin (A2) may preferably include a structural unit other than thestructural unit (a1). Examples of the structural unit other than thestructural unit (a1) include a structural unit having no acid-labilegroup (which is sometimes referred to as “structural unit (s)”), astructural unit other than the structural unit (a1), a structural unit(a2) as described later and a structural unit (a3) as described later(which is sometimes referred to as “structural unit (t)”).

<Structural Unit (a1)>

The structural unit (a1) is derived from a monomer having an acid-labilegroup (which is sometimes referred to as “monomer (a1)”).

In the resin (A2), the acid-labile group contained in the structuralunit (a1) is preferably the following group (1) and/or group (2):

wherein R^(a1) to R^(a3) each independently represent a C₁ to C₈ alkylgroup, a C₃ to C₂₀ alicyclic hydrocarbon group or combination thereof,or R^(a1) and R^(a2) may be bonded together with a carbon atom bondedthereto to form a C₃ to C₂₀ divalent alicyclic hydrocarbon group;

na represents an integer of 0 or 1; and

* represents a binding site;

wherein R^(a1′) and R^(a2′) each independently represent a hydrogen atomor a C₁ to C₁₂ hydrocarbon group, R^(a3′) represents a C₁ to C₂₀hydrocarbon group, or R^(a2′) and R^(a3′) may be bonded together with acarbon atom and X bonded thereto to form a divalent C₃ to C₂₀heterocyclic group, and a methylene group contained in the hydrocarbongroup or the divalent heterocyclic group may be replaced by an oxygenatom or a sulfur atom;

X represents —O— or —S—; and

* represents a binding site.

Examples of the alkyl group of R^(a1) to R^(a3) include methyl, ethyl,propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group of R^(a1) to R^(a3) includemonocyclic groups such as a cycloalkyl group, i.e., cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl groups; and polycyclic groups suchas decahydronaphtyl, adamantyl and norbornyl groups as well as thefollowing groups. In each of the formulae, * represents a binding site.

The carbon number of the alicyclic hydrocarbon group of R^(a1) to R^(a3)is preferably 3 to 16.

Examples of groups combining the alkyl group and the alicyclichydrocarbon group include methyl cyclohexyl, dimethyl cyclohexyl, methylnorbornyl and cyclohexylmethl, adamantylmethyl and norbornyletyl groups.

na is preferably 0.

When R^(a1) and R^(a2) is bonded together to form a divalent alicyclichydrocarbon group, examples of the group —C(R^(a1))(R^(a2))(R^(a3))include the following groups. The carbon number of the divalentalicyclic hydrocarbon group is preferably 3 to 12. In each of theformulae, * represent a binding site to —O—.

In each formula, R^(a3) is as defined above.

Specific examples of the group represented by the formula (1) include,for example,

1,1-dialkylalkoxycarbonyl group (a group in which R^(a1) to R^(a3) arealkyl groups, preferably tert-butoxycarbonyl group, in the formula (1)),

2-alkyladamantane-2-yloxycarbonyl group (a group in which R^(a1), R^(a2)and a carbon atom form adamantyl group, and R^(a3) is alkyl group, inthe formula (1)), and

1-(adamantane-1-yl)-1-alkylalkoxycarbonyl group (a group in which R^(a1)and R^(a2) are alkyl group, and R^(a3) is adamantyl group, in theformula (1)).

The hydrocarbon group of R^(a3) to R^(a3′) includes any of an alkylgroup, an alicyclic hydrocarbon group, an aromatic hydrocarbon group anda group formed by combining thereof.

Examples of the alkyl group and the alicyclic hydrocarbon group are thesame examples as described above.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, naphthyl, anthryl, p-methylphenyl, p-tert-butylphenyl,p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the divalent heterocyclic group formed by bonding withR^(a2′) and R^(a3′) include the following groups.

In each formula, R^(a1′) and X are as defined above.

At least one of R^(a1′) and R^(a2′) is preferably a hydrogen atom.

Specific examples of the group represented by the formula (2) includethe following groups. In each of the formulae, * represents a bindingsite.

The monomer (a1) is preferably a monomer having an acid-labile group andan ethylenically unsaturated bond, and more preferably a (meth)acrylicmonomer having an acid-labile group.

Among the (meth)acrylic monomer having an acid-labile group, a monomerhaving a C₅ to C₂₀ alicyclic hydrocarbon group is preferred. When aresin (A2) including a structural unit derived from a monomer (a1)having a bulky structure such as the alicyclic hydrocarbon group is usedfor a resist composition, the resist composition having excellentresolution tends to be obtained.

Examples of a structural unit derived from the (meth)acrylic monomerhaving the group represented by the formula (1) preferably includestructural units represented by the formula (a1-0), the formula (a1-1)and the formula (a1-2) below. These may be used as a single structuralunit or as a combination of two or more structural units. The structuralunit represented by the formula (a1-0), the structural unit representedby the formula (a1-1) and a structural unit represented by the formula(a1-2) are sometimes referred to as “structural unit (a1-0)”,“structural unit (a1-1)” and “structural unit (a1-2)”), respectively,and monomers inducing the structural unit (a1-0), the structural unit(a1-1) and the structural unit (a1-2) are sometimes referred to as“monomer (a1-0)”, “monomer (a1-1)” and “monomer (a1-2)”), respectively:

wherein L^(a01) represents —O— or —O—(CH₂)_(k01)—CO—O—,

k01 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a01) represents a hydrogen atom or a methyl group, and

R^(a02), R^(a03) and R^(a04) each independently represent a C₁ to C₈alkyl group, a C₃ to C₁₈ alicyclic hydrocarbon group or a combinationthereof.

L^(a01) is preferably an —O— or *—O—(CH₂)_(k01)—CO—O— in which k01 ispreferably an integer of 1 to 4, more preferably an integer of 1, morepreferably an —O—.

Examples of the alkyl group and an alicyclic hydrocarbon group ofR^(a02), R^(a03) and R^(a04) and the combination thereof are the sameexamples as the group described in R^(a1) to R^(a3) in the formula (1).

The alkyl group of R^(a02), R^(a03) and R^(a04) is preferably a C₁ to C₆alkyl group.

The alicyclic hydrocarbon group of R^(a02), R^(a03) and R^(a04) ispreferably a C₃ to C₈ alicyclic hydrocarbon group, more preferably a C₃to C₆ alicyclic hydrocarbon group.

The group formed by combining the alkyl group and the alicyclichydrocarbon group has preferably 18 or less of carbon atom. Examples ofthose groups include methylcyclohexyl, dimethylcyclohexyl andmethylnorbornyl groups.

R^(a02) and R^(a03) is preferably a C₁ to C₆ alkyl group, morepreferably a methyl or ethyl group.

R^(a04) is preferably a C₁ to C₆ alkyl group or a C₅ to C₁₂ alicyclichydrocarbon group, more preferably methyl, ethyl, cyclohexyl oradamantyl group.

In each formula, L^(a1) and L^(a2) each independently represent —O— or*—O—(CH₂)_(k1)—CO—O—,

k1 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a4) and R^(a5) each independently represent a hydrogen atom or amethyl group,

R^(a6) and R^(a7) each independently represent a C₁ to C₈ alkyl group, aC₃ to C₁₈ alicyclic hydrocarbon group or a combination thereof,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.

L^(a1) and L^(a2) are preferably —O— or *—O—(CH₂)_(k1′)—CO—O— in whichk1′ represents an integer of 1 to 4 and more preferably 1, and stillmore preferably —O—.

R^(a4) and R^(a5) are preferably a methyl group.

Examples of the alkyl group of R^(a6) and R^(a7) include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group of R^(a6) and R^(a7) includemonocyclic hydrocarbon groups such as a cycloalkyl group, i.e.,cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl, cyclobutyl and cyclodecyl groups; andpolycyclic hydrocarbon groups such as decahydronaphtyl, adamantyl,2-alkyadamantane-2-yl, 1-(adamantane-1-yl) alkane-1-yl, norbornyl,methyl norbornyl and isobornyl groups.

Examples of group formed by combining the alkyl group and the alicyclichydrocarbon group of R^(a6) and R^(a7) include an aralkyl group such asbenzyl and phenethyl groups.

The alkyl group of R^(a6) and R^(a7) is preferably a C₁ to C₆ alkylgroup.

The alicyclic hydrocarbon group of R^(a6) and R^(a7) is preferably a C₃to C₈ alicyclic hydrocarbon group, and more preferably a C₃ to C₆alicyclic hydrocarbon group.

m1 is preferably an integer of 0 to 3, and more preferably 0 or L

n1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1′ is preferably 0 or 1, and more preferably 1.

Examples of the monomer (a1-0) preferably include monomers representedby formula (a1-0-1) to formula (a1-0-12), and more preferably monomersrepresented by formula (a1-0-1) to formula (a1-0-10) below.

Examples of the structural units (a1-0) include structural units inwhich a methyl group corresponding to R^(a01) has been replaced by ahydrogen atom in the structural units represented by the above formulae.

Examples of the monomer (a1-1) include monomers described in JP2010-204646A. Among these, the monomers are preferably monomersrepresented by formula (a1-1-1) to formula (a1-1-8), and more preferablymonomers represented by formula (a1-1-1) to formula (a1-1-4) below.

Examples of the monomer (a1-2) include 1-methylcyclopentane-1-yl(meth)acrylate, 1-ethylcyclopentane-1-yl (meth)acrylate,1-methylcyclohexane-1-yl (meth)acrylate, 1-ethylcyclohexane-1-yl(meth)acrylate, 1-ethylcycloheptane-1-yl (meth)acrylate,1-ethylcyclooctane-1-yl (meth)acrylate, 1-isopropylcyclopentane-1-yl(meth)acrylate and 1-isopropylcyclohexane-1-yl (meth)acrylate. Amongthese, the monomers are preferably monomers represented by formula(a1-2-1) to formula (a1-2-12), and more preferably monomers representedby formula (a1-2-3), formula (a1-2-4), formula (a1-2-9) and formula(a1-2-10), and still more preferably monomer represented by formula(a1-2-3) and formula (a1-2-9) below.

When the resin (A2) includes the structural unit (a1-0) and/or thestructural unit (a1-1) and/or the structural unit (a1-2), the totalproportion thereof is generally 10 to 95% by mole, preferably 15 to 90%by mole, and more preferably 20 to 85% by mole, with respect to thetotal structural units (100% by mole) of the resin (A2).

Further, examples of the structural unit (a1) having the group (1)include a structural unit presented by formula (a1-3). The structuralunit represented by the formula (a1-3) is sometimes referred to as“structural unit (a1-3)”. The monomer from which the structural unit(a1-3) is derived is sometimes referred to as “monomer (a1-3)”.

In the formula, R^(a9) represents a carboxy group, a cyano group, a—COOR^(a13), a hydrogen atom or a C₁ to C₃ aliphatic hydrocarbon groupthat may have a hydroxy group,

R^(a13) represents a C₁ to C₈ aliphatic hydrocarbon group, a C₃ to C₂₀alicyclic hydrocarbon group or a group formed by combining thereof, ahydrogen atom contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by a hydroxy group, amethylene group contained in the aliphatic hydrocarbon group and thealicyclic hydrocarbon group may be replaced by an oxygen atom or acarbonyl group, and

R^(a10), R^(a11) and R^(a12) each independently represent a C₁ to C₈alkyl group, a C₃ to C₂₀ alicyclic hydrocarbon group or a group formedby combining thereof, or R^(a10) and R^(a11) may be bonded together witha carbon atom bonded thereto to form a C₁ to C₂₀ divalent hydrocarbongroup.

Here, examples of —COOR^(a13) group include a group in which a carbonylgroup is bonded to the alkoxy group, such as methoxycarbonyl andethoxycarbonyl groups.

Examples of the aliphatic hydrocarbon group that may have a hydroxygroup of Rag include methyl, ethyl, propyl, hydroxymethy and2-hydroxyethyl groups.

Examples of the C₁ to C₈ aliphatic hydrocarbon group of R^(a13) includemethyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl,n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the C₃ to C₂₀ alicyclic hydrocarbon group of R^(a13) includecyclopentyl, cyclopropyl, adamantyl, adamantylmetyl,1-(adamantyl-1-yl)-methylethyl, 2-oxo-oxolane-3-yl, 2-oxo-oxolane-4-ylgroups.

Examples of the alkyl group of R^(a10) to R^(a12) include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl,n-heptyl, 2-ethylhexyl and n-octyl groups.

Examples of the alicyclic hydrocarbon group of R^(a10) and R^(a12)include monocyclic groups such as a cycloalkyl group, i.e., cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, methylcyclohexyl,dimethylcyclohexyl, cycloheptyl, cyclooctyl and cyclodecyl groups; andpolycyclic groups such as decahydronaphtyl, adamantyl,2-alkyl-2-adamantyl, 1-(adamantane-1-yl) alkane-1-yl, norbornyl, methylnorbornyl and isobornyl groups.

When R^(a10) and R^(a11) are bonded together with a carbon atom bondedthereto to form a divalent hydrocarbon group, examples of thegroup-C(R^(a10))(R^(a11))(R^(a12)) include the following groups.

In each formula, R^(a12) is as defined above.

Examples of the monomer (a1-3) include tert-butyl5-norbornene-2-carboxylate, 1-cyclohexyl-1-methylethyl5-norbornene-2-carboxylate, 1-methylcyclohexyl5-norbornene-2-carboxylate, 2-methy-2-adamantane-2-yl5-norbornene-2-carboxylate, 2-ethyl-2-adamantane-2-yl5-norbornene-2-carboxylate, 1-(4-methylcyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-(4-hydroxycyclohexyl)-1-methylethyl5-norbornene-2-carboxylate, 1-methyl-(4-oxocyclohexyl)-1-ethyl5-norbornene-2-carboxylate, and 1-(1-adamantane-1-yl)-1-methylethyl5-norbornene-2-carboxylate.

The resin (A2) including the structural unit (a1-3) can improve theresolution of the obtained resist composition because it has a bulkystructure, and also can improve a dry-etching tolerance of the obtainedresist composition because of incorporated a rigid norbornene ring intoa main chain of the resin (A2).

When the resin (A2) includes the structural unit (a1-3), the proportionthereof is preferably 10% by mole to 95% by mole, more preferably 15% bymole to 90% by mole, and still more preferably 20% by mole to 85% bymole, with respect to the total structural units constituting the resin(A2) (100% by mole).

Examples of a structural unit (a1) having the group (2) include astructural unit represented by formula (a1-4). The structural unit issometimes referred to as “structural unit (a1-4)”.

In the formula, R^(a32) represents a hydrogen atom, a halogen atom or aC₁ to C₆ alkyl group that may have a halogen atom,

R^(a33) in each occurrence independently represent a halogen atom, ahydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a C₂ toC₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group ormethacryloyloxy group,

1a represents an integer 0 to 4,

R^(a34) and R^(a35) each independently represent a hydrogen atom or a C₁to C₁₂ hydrocarbon group; and

R^(a36) represents a C₁ to C₂₀ hydrocarbon group, or R^(a35) and R^(a36)may be bonded together with a C—O bonded thereto to form a divalent C₂to C₂₀ hydrocarbon group, and a methylene group contained in thehydrocarbon group or the divalent hydrocarbon group may be replaced byan oxygen atom or a sulfur atom.

Examples of the alkyl group of R^(a32) and R^(a33) include methyl,ethyl, propyl, isopropyl, butyl, pentyl and hexyl groups. The alkylgroup is preferably a C₁ to C₄ alkyl group, and more preferably a methylor ethyl group, and still more preferably a methyl group.

Examples of the halogen atom of R^(a32) and R^(a33) include a fluorine,chlorine, bromine and iodine atoms.

Examples of the alkyl group that may have a halogen atom includetrifluoromethyl, difluoromethyl, methyl, perfluoromethyl,1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl, perfluoropropyl,1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

Examples of an alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy and hexyloxy groups. The alkoxy group is preferably a C₁ to C₄alkoxy group, more preferably a methoxy group and an ethoxy group, andstill more preferably a methoxy group.

Examples of the acyl group include acetyl, propanonyl and butylylgroups.

Examples of the acyloxy group include acetyloxy, propanonyloxy andbutylyloxy groups.

Examples of the hydrocarbon group of R^(a34) and R^(a35) are the sameexamples as described in R^(a1′) to R^(a2′) in the formula (2).

Examples of hydrocarbon group of R^(a36) include a C₁ to C₁₈ alkylgroup, a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a group formed by combining thereof.

In the formula (a1-4), R^(a32) is preferably a hydrogen atom.

R^(a33) is preferably a C₁ to C₄ alkoxy group, more preferably a methoxygroup and an ethoxy group, and still more preferably a methoxy group.

1a is preferably 0 or 1, and more preferably 0.

R^(a34) is preferably a hydrogen atom.

R^(a35) is preferably a C₁ to C₁₂ hydrocarbon group, and more preferablya methyl or an ethyl group.

The hydrocarbon group of R^(a36) is preferably a C₁ to C₁₈ alkyl group,a C₃ to C₁₈ alicyclic hydrocarbon group, a C₆ to C₁₈ aromatichydrocarbon group or a combination thereof, and more preferably a C₁ toC₁₈ alkyl group, a C₃ to C₁₈ alicyclic hydrocarbon group or a C₇ to C₁₈aralkyl group. The alkyl group and the alicyclic hydrocarbon group ofR^(a36) are preferably unsubstituted. When the aromatic hydrocarbongroup of R^(a36) has a substituent, the substituent is preferably a C₆to C₁₀ aryloxy group.

Examples of the monomer from which the structural unit (a1-4) is derivedinclude monomers described in JP 2010-204646A. Among these, the monomersare preferably the following monomers represented by the formula(a1-4-1) to the formula (a1-4-7), and more preferably monomersrepresented by the formula (a1-4-1) to the formula (a1-4-5).

When the resin (A2) includes the structural unit (a1-4), the proportionthereof is preferably 10% by mole to 95% by mole, more preferably 15% bymole to 90% by mole, and still more preferably 20% by mole to 85% bymole, with respect to the total structural units constituting the resin(A2) (100% by mole).

Examples of the structural unit having an acid-labile group include astructural unit represented by formula (a1-5). The structural unit issometimes referred to as “structural unit (a1-5)”.

In the formula (a1-5), R^(a8) represents a hydrogen atom, a halogen atomor a C₁ to C₆ alkyl group that may have a halogen atom,

Z^(a1) represent a single bond or *—(CH₂)_(h3)—CO-L⁵⁴-,

h3 represents an integer of 1 to 4,

* represents a binding site to L⁵¹,

L⁵¹, L⁵² and L⁵³ each independently represent —O— or —S—,

s1 represents an integer of 1 to 3, and

s1′ represents an integer of 0 to 3.

In the formula (a1-5), R^(a8) is preferably a hydrogen atom, a methylgroup or trifluoromethyl group;

L⁵¹ is preferably —O—;

L⁵² and L⁵³ are independently preferably —O— or —S—, and more preferablyone is —O— and another is —S—.

s1 is preferably 1;

s1′ is preferably an integer of 0 to 2; Z^(a1) is preferably a singlebond or *—CH₂—CO—O—.

Examples of a monomer from which the structural unit (a1-5) is derivedinclude a monomer described in JP 2010-61117A. Among these, the monomersare preferably monomers represented by the formula (a1-5-1) to theformula (a1-5-4), and more preferably monomers represented by theformula (a1-5-1) to the formula (a1-5-2) below.

When the resin (A2) includes the structural unit (a1-5), the proportionthereof is preferably 1% by mole to 50% by mole, more preferably 3% bymole to 45% by mole, and more preferably 5% by mole to 40% by mole, withrespect to the total structural units (100% by mole) constituting theresin (A2).

The resin (A2) includes, as the structural unit (a1), preferably atleast one, more preferably two or more structural units selected fromthe structural unit (a1-0), the structural unit (a1-1), the structuralunit (a1-2) and the structural unit (a1-5), still more preferably acombination of the structural unit (a1-1) and the structural unit(a1-2), a combination of the structural unit (a1-1) and the structuralunit (a1-5), a combination of the structural unit (a1-1) and thestructural unit (a1-0), a combination of the structural unit (a1-2) andthe structural unit (a1-0), a combination of the structural unit (a1-5)and the structural unit (a1-0), a combination of the structural unit(a1-0), the structural unit (a1-1) and the structural unit (a1-2), acombination of the structural unit (a1-0), the structural unit (a1-1)and the structural unit (a1-5). In particular, the resin (A2) includes,as the structural unit (a1), preferably at least one of the structuralunit (a1-1) and the structural unit (a1-2) and more preferably thestructural unit (a1-1) and the structural unit (a1-2).

<Structural Unit (s)>

The structural unit (s) is derived from a monomer having no acid-labilegroup (which monomer is sometimes referred to as “monomer (s)”).

As the monomer (s) from which the structural unit (s) is derived, aknown monomer having no acid-labile group can be used.

As the structural unit (s), a structural unit having a hydroxy group ora lactone ring but having no acid-labile group is preferred. When aresin including the structural unit derived from a structural unithaving a hydroxy group but having no acid-labile group (such structuralunit is sometimes referred to as “structural unit (a2)”) and/or astructural unit having a lactone ring but having no acid-labile group(such structural unit is sometimes referred to as “structural unit(a3)”) is used, the adhesiveness of resist to a substrate and resolutionof resist pattern tend to be improved.

<Structural Unit (a2)>

The structural unit (a2) having a hydroxy group may be an alcoholichydroxy group or a phenolic hydroxy group.

When KrF excimer laser lithography (248 nm), or high-energy irradiationsuch as electron beam or EUV (extreme ultraviolet) is used for theresist composition, using the structural unit having a phenolic hydroxygroup as the structural unit (a2) is preferred.

When ArF excimer laser lithography (193 nm) is used, using thestructural unit having an alcoholic hydroxy group as the structural unit(a2) is preferred, and using the structural unit represented by theformula (a2-1) is more preferred.

The structural unit (a2) may be used as a single structural unit or as acombination of two or more structural units.

Examples of the structural unit (a2) having a phenolic hydroxy groupinclude a structural unit represented by the formula (a2-0) (which issometimes referred to as “structural unit (a2-0)”).

wherein R^(a30) represents a hydrogen atom, a halogen atom or a C₁ to C₆alkyl group that may have a halogen atom,

R^(a31) in each occurrence independently represents a halogen atom, ahydroxy group, a C₁ to C₆ alkyl group, a C₁ to C₆ alkoxy group, a C₂ toC₄ acyl group, a C₂ to C₄ acyloxy group, an acryloyloxy group ormethacryloyloxy group, and

ma represents an integer 0 to 4.

Examples of the alkyl group include methyl, ethyl, propyl, isopropyl,butyl, n-pentyl and n-hexyl groups.

Examples of the halogen atom include a chlorine atom, a fluorine atomand bromine atom.

Examples of a C₁ to C₆ alkyl group that may have a halogen atom ofR^(a30) include trifluoromethyl, difluoromethyl, methyl,perfluoromethyl, 1,1,1-trifluoroethyl, 1,1,2,2-tetrafluoroethyl, ethyl,perfluoropropyl, 1,1,1,2,2-pentafluoropropyl, propyl, perfluorobutyl,1,1,2,2,3,3,4,4-octafluorobutyl, butyl, perfluoropentyl,1,1,1,2,2,3,3,4,4-nonafluoropentyl, n-pentyl, n-hexyl andn-perfluorohexyl groups.

R^(a30) is preferably a hydrogen atom or a C₁ to C₄ alkyl group, andmore preferably a hydrogen atom, methyl or ethyl group, and still morepreferably a hydrogen atom or methyl group.

Examples of a C₁ to C₆ alkoxy group of R^(a31) include methoxy, ethoxy,propoxy, butoxy, pentyloxy, and hexyloxy groups. R^(a31) is preferably aC₁ to C₄ alkoxy group, more preferably a methoxy and ethoxy group, andstill more preferably methoxy group.

Examples of the acyl group include acetyl, propanonyl and butylylgroups.

Examples of the acyloxy group include acetyloxy, propanonyloxy andbutylyloxy groups.

ma is preferably 0, 1 or 2, more preferably 0 or 1, still morepreferably 0.

The structural unit (a2-0) having a phenolic hydroxy group is preferablya structural unit represented below.

Among these, a structural unit represented by the formula (a2-0-1) andthe formula (a2-0-2) are preferred.

Examples of a monomer from which the structural unit (a2-0) is derivedinclude monomers described in JP2010-204634A.

The resin (A2) which includes the structural units (a2) having aphenolic hydroxy group can be produced, for example, by polymerizing amonomer where its phenolic hydroxy group has been protected with asuitable protecting group, followed by deprotection. The deprotection iscarried in such a manner that an acid-labile group in the structuralunit (a1) is significantly impaired. Examples of the protecting groupfor a phenolic hydroxy group include an acetyl group.

When the resin (A2) includes the structural unit (a2-0) having thephenolic hydroxy group, the proportion thereof is preferably 5% by moleto 95% by mole, more preferably 10% by mole to 80% by mole, and stillmore preferably 15% by mole to 80% by mole, with respect to the totalstructural units (100% by mole) constituting the resin (A).

Examples of the structural unit (a2) having an alcoholic hydroxy groupinclude the structural unit represented by the formula (a2-1) (which issometimes referred to as “structural unit (a2-1)”).

In the formula (a2-1), L^(a3) represents —O— or *—O—(CH₂)_(k2)—CO—O—,

k2 represents an integer of 1 to 7,

* represents a binding site to —CO—,

R^(a14) represents a hydrogen atom or a methyl group,

R^(a15) and R^(a16) each independently represent a hydrogen atom, amethyl group or a hydroxy group, and

o1 represents an integer of 0 to 10.

In the formula (a2-1), L^(a3) is preferably —O—, —O—(CH₂)_(f1)—CO—O—,here f1 represents an integer of 1 to 4, and more preferably —O—.

R^(a14) is preferably a methyl group.

R^(a15) is preferably a hydrogen atom.

R^(a16) is preferably a hydrogen atom or a hydroxy group.

o1 is preferably an integer of 0 to 3, and more preferably an integer of0 or 1.

Examples of the monomer from which the structural unit (a2-1) is derivedinclude monomers described in JP 2010-204646A. Among these, thestructural units (a2-1) are preferably structural units represented bythe formula (a2-1-1) to the formula (a2-1-6), more preferably structuralunits represented by the formula (a2-1-1) to the formula (a2-1-4), andstill more preferably structural units represented by the formula(a2-1-1) and the formula (a2-1-3).

When the resin (A2) includes the structural unit (a2-1) having analcoholic hydroxy group, the proportion thereof is generally 1% by moleto 45% by mole, preferably 1% by mole to 40% by mole, more preferably 1%by mole to 35% by mole, and still more preferably 2% by mole to 20% bymole, with respect to the total structural units (100% by mole)constituting the resin (A2).

<Structural Unit (a3)>

The lactone ring included in the structural unit (a3) may be amonocyclic ring such as β-propiolactone, γ-butyrolactone,δ-valerolactone, or a condensed ring of monocyclic lactone ring withanother ring. Examples of the lactone ring preferably includeγ-butyrolactone, amadantane lactone, or bridged ring withγ-butyrolactone.

Examples of the structural unit (a3) include structural unitsrepresented by any of formula (a3-1), formula (a3-2), formula (a3-3) andformula (a3-4). These structural units may be used as a single unit oras a combination of two or more units.

In each formula, L^(a4) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3represents an integer of 1 to 7, * represents a binding site to acarbonyl group,

R^(a18) represents a hydrogen atom or a methyl group,

R^(a21) in each occurrence represents a C₁ to C₄ aliphatic hydrocarbongroup, and

p1 represents an integer of 0 to 5,

L^(a5) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3 represents an integerof 1 to 7, represents a binding site to a carbonyl group,

R^(a19) represents a hydrogen atom or a methyl group,

R^(a22) in each occurrence represents a carboxy group, a cyano group ora C₁ to C₄ aliphatic hydrocarbon group,

q1 represents an integer of 0 to 3,

L^(a6) represents *—O— or *—O—(CH₂)_(k3)—CO—O—, k3 represents an integerof 1 to 7, * represents a binding site to a carbonyl group,

R^(a20) represents a hydrogen atom or a methyl group,

R^(a23) in each occurrence represents a carboxy group, a cyano group ora C₁ to C₄ aliphatic hydrocarbon group, and

r1 represents an integer of 0 to 3,

R^(a24) represents a hydrogen atom, a halogen atom or a C₁ to C₆ alkylgroup that may have a halogen atom,

L^(a7) represents a single bond, *-L^(a8)-O—, *-L^(a8)-CO—O—,*-L^(a8)-CO—O-L^(a9)-CO—O—, or *-L^(a8)-O—CO-L^(a9)-O—; * represents abinding site to a carbonyl group, and

L^(a8) and L^(a9) each independently represent a C₁ to C₆ alkanediylgroup.

Examples of the aliphatic hydrocarbon group of R^(a21), R^(a2) andR^(a23) include an alkyl group such as methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl and tert-butyl groups.

Examples of the halogen atom of R^(a24) include fluorine, chlorine,bromine and iodine atoms;

Examples of the alkyl group of R^(a24) include methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl and n-hexyl groups,preferably a C₁ to C₄ alkyl group, more preferably methyl and ethylgroups.

Examples of the alkyl group having a halogen atom of R^(a24) includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl, perfluorohexyl, trichloromethyl, tribromomethyl andtriiodomethyl groups.

Examples of the alkanediyl group of L^(a8) and L^(a9) include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, butane-1,3-diyl,2-methylpropane-1,3-diyl, 2-methylpropane-1,2-diyl, pentane-1,4-diyl and2-methylbutane-1,4-diyl groups.

In the formulae (a3-1) to (a3-3), L^(a8) to L^(a9) is independentlypreferably —O—, *—O—(CH₂)_(k3)′—CO—O—, here k3′ represents an integer of1 to 4, more preferably —O— or *—O—CH₂—CO—O—, and still more preferably*—O—.

R^(a18) to R^(a21) is preferably a methyl group.

R^(a22) and R^(a23) are independently preferably a carboxy group, acyano group or a methyl group.

p1, q1 and r1 are independently preferably an integer of 0 to 2, andmore preferably 0 or 1.

In the formula (a3-4), R^(a24) is preferably a hydrogen atom or a C₁ toC₄ alkyl group, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

L^(a1) is preferably a single bond or -L^(a8)—CO—O—, and more preferablya single bond, —CH₂—CO—O— or —C₂H₄—CO—O—.

Examples of the monomer from which the structural unit (a3) is derivedinclude monomers described in JP 2010-204646A, monomers described inJP2000-122294A and monomers described in JP2012-41274A. The structuralunits (a3) are preferably structural units represented by the formula(a3-1-1) to the formula (a3-1-4), the formula (a3-2-1) to the formula(a3-2-4), the formula (a3-3-1) to the formula (a3-3-4), the formula(a3-4-1) to the formula (a3-4-12), more preferably structural unitsrepresented by the formula (a3-1-1) to the formula (a3-1-2), the formula(a3-2-3), the formula (a3-2-4), the formula (a3-4-1) and the formula(a3-4-12), still more preferably structural units represented by theformula (a3-4-1) and the formula (a3-4-12), and further still preferablythe formula (a3-4-1) to the formula (a3-4-6) below.

Examples of the structural unit (a3) include the structural unitsrepresented by the formula (a3-4-1) to the formula (a3-4-12) and thosein which a methyl group corresponding to R^(a24) has been replaced by ahydrogen atom in the structural units represented by the above formulae.

When the resin (A2) includes the structural units (a3), the totalproportion thereof is preferably 5% by mole to 70% by mole, morepreferably 10% by mole to 65% by mole, still more preferably 10% by moleto 60% by mole, with respect to the total structural units (100% bymole) constituting the resin (A2).

The proportion each of the formula (a3-1), the formula (a3-2), theformula (a3-3) and the formula (a3-4) is preferably 5% by mole to 60% bymole, more preferably 5% by mole to 50% by mole, still more preferably10% by mole to 50% by mole, with respect to the total structural units(100% by mole) constituting the resin (A2).

<Other Structural Unit (t)>

The resin (A2) may further include a structural unit other than thestructural unit (a1) and the structural unit (s) described above (whichis sometimes referred to as “structural unit (t)”). Examples of thestructural unit (t) include the structural unit (a4), the structuralunit (I), and another structural unit other than the structural unit(a2) and the structural unit (a3).

When the resin (A2) includes the structural unit (a4), the proportionthereof is preferably 1 to 20% by mole, more preferably 2 to 15% bymole, and still more preferably 3 to 10% by mole, with respect to thetotal structural units (100% by mole) of the resin (A2).

When the resin (A2) includes the structural unit (I), the proportionthereof is preferably 1 to 30% by mole, more preferably 2 to 20% bymole, and still more preferably 3 to 15% by mole, with respect to thetotal structural units (100% by mole) of the resin (A2).

The resin (A2) is preferably a resin having the structural unit (a1) andthe structural unit (s), that is, a copolymer of the monomer (a1) andthe monomer (s). In this copolymer, the structural unit (a1) ispreferably at least one of the structural unit (a1-1), the structuralunit (a1-2) (preferably the structural unit having a cyclohexyl group ora cyclopentyl group) and the structural unit (a1-5), and more preferablyis the structural unit (a1-1) or the structural unit (a1-2) (preferablythe structural unit having a cyclohexyl group or a cyclopentyl group).

The structural unit (s) is preferably at least one of the structuralunit (a2) and the structural unit (a3). The structural unit (a2) ispreferably the structural unit represented by the formula (a2-1). Thestructural unit (a3) is preferably the structural unit having at leastone of a γ-butyrolactone ring, a bridged ring including aγ-butyrolactone ring or an adamantane lactone ring, i.e., the structuralunits (a3-1-1) to (a3-1-4), the structural units (a3-2-1) to (a3-2-4)and the structural units (a3-4-1) to (a3-4-2).

The proportion of the structural unit derived from the monomer having anadamantyl group (in particular, the structural unit (a1-1)) in the resin(A2) is preferably 15% by mole or more with respect to the structuralunits (a1). As the mole ratio of the structural unit derived from themonomer having an adamantyl group increases within this range, the dryetching resistance of the resulting resist improves.

The resin (A2) can be produced by a known polymerization method, forexample, radical polymerization method, using one or more species ofmonomers inducing the structural units as described above. Theproportion of the structural unit in the resin (A2) can be adjusted bychanging the amount of a monomer used in polymerization.

The weight average molecular weight of the resin (A2) is preferably2,000 or more (more preferably 2,500 or more, and still more preferably3,000 or more), and 50,000 or less (more preferably 30,000 or less, andstill more preferably 15,000 or less).

The proportion of the resin (A1) is preferably 1 to 60 parts by mass,more preferably 1 to 50 parts by mass, and still more preferably 1 to 40parts by mass, in particular preferably 2 to 30 parts by mass, withrespect to the resin (A2) (100 parts by mass).

<Resin (X)>

The resist composition of the disclosure may include a resin (X) otherthan the resin (A1) and the resin (A2). Examples of the resin (X)include a resin consisting of the structural unit (s) such as thestructural unit (a2), the structural unit (a3).

The weight average molecular weight of the resin (X) is preferably 6,000or more (more preferably 7,000 or more), and 80,000 or less (morepreferably 60,000 or less). The method of measuring of the weightaverage molecular weight of the resin (X) is the same as the resin (A1).

When the resist composition includes the resin (X), the proportionthereof is preferably 1 to 60 parts by mass, more preferably 1 to 50parts by mass, and still more preferably 1 to 40 parts by mass, inparticular preferably 2 to 30 parts by mass, with respect to the resin(A1) (100 parts by mass).

The total proportion of the resin (A1) and the resin (A2) is preferably80% by mass to 99% by mass, more preferably 90% by mass to 99% by mass,with respect to the total amount of solid components of the resistcomposition.

When the resist composition includes the resin (X), the total proportionof the resin (A1), the resin (A2) and the resin (X) is preferably 80% bymass to 99% by mass, more preferably 90% by mass to 99% by mass, withrespect to the total amount of solid components of the resistcomposition.

The proportion of the solid components in the resist composition andthat of the resins in the solid components can be measured with a knownanalytical method such as liquid chromatography and gas chromatography.

<Acid Generator (B)>

The acid generator (B) may be an ionic acid generator or a non-ionicacid generator. The acid generator (B) may be used any an ionic acidgenerator and a non-ionic acid generator. Examples of the nonioniccompounds for the acid generator include organic halogenated compounds;sulfonate esters, e.g. 2-nitrobenzylester, aromatic sulfonates,oximesulfonate, N-sulfonyloxyimide, sulfonyloxyketone, anddiazonaphtoquione 4-sulfonate; sulfones, e.g., disulfone, ketosulfone,and sulfonium diazomethane. The ionic compounds for the acid generatorinclude onium salts having an onium cation, e.g., diazonium salts,phosphonium salts, sulfonium salts and iodonium salts. Examples of theanions of onium salt include a sulfonic acid anion, a sulfonylimideanion, sulfonylmethide anion.

As the acid generator, the compounds giving an acid by radiation can beused, which are mentioned in JP63-26653A1, JP55-164824A1, JP62-69263A1,JP63-146038A1, JP63-163452A1, JP62-153853A1, JP63-146029A1, U.S. Pat.No. 3,779,778B1, U.S. Pat. No. 3,849,137B1, DE3914407 and EP126,712A1.The acid generator for the photoresist composition can be produced bythe method described in the above-mentioned documents.

The acid generator is preferably a fluorine-containing compound, morepreferably a salt represented by formula (B1) (which is sometimesreferred to as “acid generator (B1)”):

wherein Q¹ and Q² each respectively represent a fluorine atom or a C₁ toC₆ perfluoroalkyl group,

L^(b1) represents a C₁ to C₂₄ divalent saturated hydrocarbon group wherea methylene group may be replaced by an oxygen atom or a carbonyl groupand a hydrogen atom may be replaced by a hydroxyl group or fluorineatom, and

Y represents an optionally substituted C₃ to C₁₈ alicyclic hydrocarbongroup where a methylene group may be replaced by an oxygen atom, acarbonyl group or a sulfonyl group, and

Z⁺ represents an organic cation.

Examples of the perfluoroalkyl group of Q¹ and Q² includetrifluoromethyl, perfluoroethyl, perfluoropropyl, perfluoro-isopropyl,perfluorobutyl, perfluoro-sec-butyl, perfluoro-tert-butyl,perfluoropentyl and perfluorohexyl groups.

Q¹ and Q² independently are preferably trifluoromethyl or fluorine atom,and both of Q¹ and Q² are more preferably a fluorine atom.

Examples of the divalent saturated hydrocarbon group of L^(b1) includeany of a chain or a branched alkanediyl group, a divalent mono- or apoly-alicyclic saturated hydrocarbon group, and a combination thereof.

Specific examples of the chain alkanediyl group include methylene,ethylene, propane-1,3-diyl, propane-1,2-diyl, butane-1,4-diyl,pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl,nonane-1,9-diyl, decane-1,10-diyl, undecane-1,11-diyl,dodecane-1,12-diyl, tridecane-1,13-diyl, tetradecane-1,14-diyl,pentadecane-1,15-diyl, hexadecane-1,16-diyl, heptadecane-1,17-diylgroups.

Specific examples of the branched chain alkanediyl group includeethane-1,1-diyl, propane-1,1-diyl, propane-1,2-diyl, propane-2,2-diyl,pentane-1,4-diyl, pentane-2,4-diyl, 2-methylpropane-1,3-diyl,2-methylpropane-1,2-diyl and 2-methylbutane-1,4-diyl groups.

Specific examples of the mono-alicyclic saturated hydrocarbon groupinclude a cycloalkanediyl group such as cyclobutan-1,3-diyl,cyclopentan-1,3-diyl, cyclohexane-1,4-diyl and cyclooctan-1,5-diylgroups.

Specific examples of the poly-alicyclic saturated hydrocarbon groupinclude norbornane-1,4-diyl, norbornane-2,5-diyl, adamantane-1,5-diyland adamantane-2,6-diyl groups.

Examples of the saturated hydrocarbon group of L^(b1) in which amethylene group has been replaced by oxygen atom or a carbonyl groupinclude the following groups represented by formula (b1-1) to formula(b1-3):

wherein L^(b2) represents a single bond or a C₁ to C₂₂ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom;

L^(b3) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the total carbon number contained in the group of L^(b2)and L^(b3) is 22 or less;

L^(b4) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b5) represents a single bond or a C₁ to C₂₂ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the total carbon number contained in the group of L^(b4)and L^(b5) is 22 or less;

L^(b6) represents a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

L^(b7) represents a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and a methylene group may be replaced by anoxygen atom or a carbonyl group;

provided that the total carbon number contained in the group of L^(b6)and L^(b7) is 23 or less, and

* represents a binding site to —Y.

In formula (b1-1) to formula (b1-3), when a methylene group has beenreplaced by an oxygen atom or a carbonyl group, the carbon number of thesaturated hydrocarbon group corresponds to the number of the carbon atombefore replacement.

Examples of the divalent saturated hydrocarbon group are the sameexamples as the divalent saturated hydrocarbon group of L^(b1).

L^(b2) is preferably a single bond.

L^(b3) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.

L^(b4) is preferably a C₁ to C₈ divalent saturated hydrocarbon groupwhere a hydrogen atom may be replaced by a fluorine atom.

L^(b5) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.

L^(b6) is preferably a single bond or a C₁ to C₄ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom.

L^(b7) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group, and where a methylene group may be replaced byan oxygen atom or a carbonyl group.

Among these, the group represented by the formula (b1-1) or the formula(b1-3) is preferred.

Examples of the divalent group represented by the formula (b1-1) includethe following groups represented by formula (b1-4) to formula (b1-8):

wherein L^(b8) represents a single bond or a C₁ to C₂₂ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom or a hydroxy group;

L^(b9) represents a C₁ to C₂₀ divalent saturated hydrocarbon group;

L^(b10) represents a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b9)and L^(b10) is 20 or less;

L^(b11) represents a C₁ to C₂₁ divalent saturated hydrocarbon group;

L^(b12) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b11)and L^(b12) is 21 or less;

L^(b13) represents a C₁ to C₁₉ divalent saturated hydrocarbon group;

L^(b14) represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group;

L^(b15) represents a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b13),L^(b14) and L^(b15) is 19 or less;

L^(b16) represents a C₁ to C₁₈ divalent saturated hydrocarbon group;

L^(b17) represents a C₁ to C₁₈ divalent saturated hydrocarbon group;

L^(b18) represents a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom or a hydroxy group;

provided that the total carbon number contained in the group of L^(b16),L^(b17) and L^(b18) is 19 or less.

L^(b8) is preferably a C₁ to C₄ divalent saturated hydrocarbon group.

L^(b9) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.

L^(b10) is preferably a single bond or a C₁ to C₁₉ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.

L^(b11) is preferably a C₁ to C₈ divalent saturated hydrocarbon group.

L^(b12) is preferably a single bond or a C₁ to C₈ divalent saturatedhydrocarbon group.

L^(b13) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.

L^(b14) is preferably a single bond or a C₁ to C₆ divalent saturatedhydrocarbon group.

L^(b15) is preferably a single bond or a C₁ to C₁₈ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₈divalent saturated hydrocarbon group.

L^(b16) is preferably a C₁ to C₁₂ divalent saturated hydrocarbon group.

L^(b17) is preferably a C₁ to C₆ divalent saturated hydrocarbon group.

L^(b18) is preferably a single bond or a C₁ to C₁₇ divalent saturatedhydrocarbon group, and more preferably a single bond or a C₁ to C₄divalent saturated hydrocarbon group.

Examples of the divalent group represented by the formula (b1-3) includethe following groups represented by formula (b1-9) to formula (b1-11):

wherein L^(b19) represents a single bond or a C₁ to C₂₃ divalentsaturated hydrocarbon group where a hydrogen atom may be replaced by afluorine atom;

L^(b20) represent a single bond or a C₁ to C₂₃ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the total carbon number contained in the group of L^(b10)and L^(b20) is 23 or less;

L^(b21) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b22) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group;

L^(b23) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the total carbon number contained in the group of L^(b21),L^(b22) and L^(b23) is 21 or less;

L^(b24) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom;

L^(b25) represents a single bond or a C₁ to C₂₁ divalent saturatedhydrocarbon group;

L^(b26) represents a single bond or a C₁ to C₂₀ divalent saturatedhydrocarbon group where a hydrogen atom may be replaced by a fluorineatom, a hydroxy group or an acyloxy group, and a methylene groupcontained in an acyloxy group may be replaced by an oxygen atom or acarbonyl group, and a hydrogen atom contained in an acyloxy group may bereplaced by a hydroxy group,

provided that the total carbon number contained in the group of L^(b24),L^(b25) and L^(b26) is 21 or less.

In formula (b1-9) to formula (b1-11), when a hydrogen atom has beenreplaced by an acyloxy group, the carbon number of the saturatedhydrocarbon group corresponds to the number of the carbon atom, CO and Oin addition to the carbon number of the saturated hydrocarbon group.

For formula (b1-9) to formula (b1-11), examples of the divalentsaturated hydrocarbon group include an alkanediyl and a monocyclic orpolycyclic divalent saturated hydrocarbon group, and a combination oftwo or more such groups.

Examples of the acyloxy group include acetyloxy, propionyloxy,butyryloxy, cyclohexyl carbonyloxy and adamantyl carbonyloxy groups.

Examples of the acyloxy group having a substituent include oxoadamantylcarbonyloxy, hydroxyadamantyl carbonyloxy, oxocyclohexyl carbonyloxy andhydroxycyclohexyl carbonyloxy groups.

Examples of the group represented by the formula (b1-4) include thefollowing ones.

Examples of the group represented by the formula (b1-5) include thefollowing ones.

Examples of the group represented by the formula (b1-6) include thefollowing ones.

Examples of the group represented by the formula (b1-7) include thefollowing ones.

Examples of the group represented by the formula (b1-8) include thefollowing ones.

Examples of the group represented by the formula (b1-2) include thefollowing ones.

Examples of the group represented by the formula (b1-9) include thefollowing ones.

Examples of the group represented by the formula (b1-10) include thefollowing ones.

Examples of the group represented by the formula (b1-11) include thefollowing ones.

Examples of the monovalent alicyclic hydrocarbon group of Y includegroups represented by formula (Y1) to formula (Y11).

Examples of the monovalent alicyclic hydrocarbon group of Y in which amethylene group has been replaced by an oxygen atom, a carbonyl group ora sulfonyl group include groups represented by formula (Y12) to formula(Y27).

Among these, the alicyclic hydrocarbon group is preferably any one ofgroups represented by the formula (Y1) to the formula (Y19), morepreferably any one of groups represented by the formula (Y11), (Y14),(Y15) or (Y19), and still more preferably group represented by theformula (Y11) or (Y14).

Examples of the substituent for the alicyclic group of Y include ahalogen atom, a hydroxyl group, a C₁ to C₁₂ alkyl group, a hydroxygroup-containing C₁ to C₁₂ alkyl group, a C₃ to C₁₆ monovalent alicyclichydrocarbon group, a C₁ to C₁₂ alkoxy group, a C₆ to C₁₈ monovalentaromatic hydrocarbon group, a C₇ to C₂₁ aralkyl group, a C₂ to C₄ acylgroup, a glycidyloxy group and —(CH₂)_(j2)—O—CO—R^(b1)— in which R^(b1)represents an C₁ to C₁₆ alkyl group, a C₃ to C₁₆ monovalent alicyclichydrocarbon group, or a C₆ to C₁₈ monovalent aromatic hydrocarbon group,and j2 represents an integer of 0 to 4.

Examples of the hydroxy group-containing alkyl group includehydroxymethyl and hydroxyethyl groups

Examples of the alkoxyl group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, decyloxy and dodecyloxygroups.

Examples of the monovalent aromatic hydrocarbon group include an arylgroup such as phenyl, naphthyl, anthryl, p-methylphenyl,p-tert-butylphenyl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl,biphenyl, phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenylgroups.

Examples of the aralkyl group include benzyl, phenethyl, phenylpropyl,naphthylmethyl and naphthylethyl groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of Y include the groups below. * represents a binding site toL^(b1).

Y is preferably a C₃ to C₁₈ monovalent alicyclic hydrocarbon group whichmay have a substituent, more preferably an adamantyl group which mayhave a substituent and one or more methylene group contained in theadamantyl group may be replaced with an oxygen atom, a carbonyl group ora sulfonyl group, and still more preferably an adamantyl group, ahydroxyadamantyl group or an oxoadamantyl group.

The sulfonic acid anion in the salt represented by the formula (B1) ispreferably an anions represented by formula (B1-A-1) to formula(B1-A-33), and more preferably an anions represented by formula (B1-A-1)to formula (B1-A-4), formula (B1-A-9), formula (B1-A-10), formula(B1-A-24) to formula (B1-A-33), below.

In the formula (B1-A-1) to the formula (B1-A-33), R′² to R¹⁷independently represent, for example, a C₁ to C₄ alkyl group, andpreferably methyl or ethyl group, R″ represent, for example, a C₁ to C₁₂aliphatic hydrocarbon group, preferably a C₁ to C₄ alkyl group, a C₅ toC₁₂ monovalent alicyclic hydrocarbon group or a group formed by acombination thereof, more preferably a methyl, ethyl group, cyclohexylgroup or adamantyl group. L⁴⁴ represents a single bond or a C₁ to C₄alkanediyl group. Q¹ and Q² represent the same meaning as defined above.

Specific examples of the sulfonic acid anion in the salt represented bythe formula (B1) include anions mentioned in JP2010-204646A1.

Among these, preferred examples of the sulfonic acid anion for the saltrepresented by the formula (B1) include anions represented by formulae(B1a-1) to (B1a-15).

Among them, preferred examples of the sulfonic acid anion include anionsrepresented by the formulae (B1a-1) to (B1a-3) and (B1a-7) to (B1a-15).

Examples of the organic cation represented by Z⁺ include an organiconium cation such as an organic sulfonium cation, an organic iodoniumcation, an organic ammonium cation, a benzothiazolium cation and anorganic phosphonium cation, and an organic sulfonium cation and anorganic iodonium cation are preferred, and an arylsulfonium cation ismore preferred.

Z⁺ of the formula (B1) is preferably represented by any of the formula(b2-1) to the formula (b2-4):

wherein R^(b4), R^(b5) and R^(b6) independently represent a C₁ to C₃₀aliphatic hydrocarbon group, a C₃ to C₃₆ alicyclic hydrocarbon group ora C₆ to C₃₆ aromatic hydrocarbon group, a hydrogen atom contained in analiphatic hydrocarbon group may be replaced by a hydroxy group, a C₁ toC₁₂ alkoxy group, a C₃ to C₁₂ alicyclic hydrocarbon group or a C₆ to C₁₈aromatic hydrocarbon group, a hydrogen atom contained in an alicyclichydrocarbon group may be replaced by a halogen atom, a C₁ to C₁₈aliphatic hydrocarbon group, a C₂ to C₄ acyl group or a glycidyloxygroup, a hydrogen atom contained in an aromatic hydrocarbon group may bereplaced by a halogen atom, a hydroxy group or a C₁ to C₁₂ alkoxy group,or R^(b4) and R^(b5) may be bonded together with a sulfur atom bondedthereto to form a sulfur-containing ring, a methylene group contained inthe ring may be replaced by an oxygen atom, a —SO— or a carbonyl group;

R^(b7) and R^(b8) in each occurrence independently represent a hydroxygroup, a C₁ to C₁₂ aliphatic hydrocarbon group or a C₁ to C₁₂ alkoxygroup,

m2 and n2 independently represent an integer of 0 to 5;

R^(b9) and R^(b10) each independently represent a C₁ to C₃₆ aliphatichydrocarbon group or a C₃ to C₃₆ alicyclic hydrocarbon group, or R^(b9)and R^(b10) may be bonded together with a sulfur atom bonded thereto toform a sulfur-containing ring, and a methylene group contained in thering may be replaced by an oxygen atom, a —SO— or a carbonyl group;

R^(b11) represents a hydrogen atom, a C₁ to C₃₆ aliphatic hydrocarbongroup, a C₃ to C₃₆ alicyclic hydrocarbon group or a C₆ to C₁₈ aromatichydrocarbon group;

R^(b12) represents a C₁ to C₁₂ aliphatic hydrocarbon group, a C₃ to C₁₈alicyclic hydrocarbon group and a C₆ to C₁₈ aromatic hydrocarbon group,a hydrogen atom contained in an aliphatic hydrocarbon group may bereplaced by a C₆ to C₁₈ aromatic hydrocarbon group, and a hydrogen atomcontained in an aromatic hydrocarbon group may be replaced by a C₁ toC₁₂ alkoxy group or a C₁ to C₁₂ alkyl carbonyloxy group;

R^(b11) and R^(b12) may be bonded together with —CH—CO— bonded theretoto form a ring, and a methylene group contained in the ring may bereplaced by an oxygen atom, a —SO— or a carbonyl group;

R^(b13), R^(b14), R^(b15), R^(b16), R^(b17) and R^(b18) in eachoccurrence independently represent a hydroxy group, a C₁ to C₁₂aliphatic hydrocarbon group or a C₁ to C₁₂ alkoxy group;

L^(b11) represents —S— or —O—;

o2, p2, s2 and t2 independently represent an integer of 0 to 5;

q2 or r2 independently represent an integer of 0 to 4; and

u2 represents an integer of 0 or 1.

Examples of the aliphatic group preferably include methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl,n-octyl and 2-ethylhexyl groups. Among these, the aliphatic hydrocarbongroup of R^(b9) to R^(b12) is preferably a C₁ to C₁₂ aliphatichydrocarbon group.

Examples of the alicyclic hydrocarbon group preferably includemonocyclic groups such as a cycloalkyl group, i.e., cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecylgroups; and polycyclic groups such as decahydronaphtyl, adamantyl andnorbornyl groups as well as the following groups. * represents a bindingsite.

Among these, the alicyclic hydrocarbon group of R^(b9) to R^(b12) ispreferably a C₃ to C₁₈ alicyclic hydrocarbon group, and more preferablya C₄ to C₁₂ alicyclic hydrocarbon group.

Examples of the alicyclic hydrocarbon group where a hydrogen atom may bereplaced by an aliphatic hydrocarbon group include methylcyclohexyl,dimethylcyclohexyl, 2-alkyladamantane-2-yl, methylnorbornyl andisobornyl groups. In the alicyclic hydrocarbon group where a hydrogenatom may be replaced by an aliphatic hydrocarbon group, the total carbonnumber of the alicyclic hydrocarbon group and the aliphatic hydrocarbongroup is preferably 20 or less.

Examples of the aromatic hydrocarbon group preferably include an arylgroup such as phenyl, tolyl, xylyl, cumenyl, mesityl, p-ethylphenyl,p-tert-butylphenyl, p-cyclohexylphenyl, p-adamantylphenyl, biphenyl,naphthyl, phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenylgroups.

When the aromatic hydrocarbon includes an aliphatic hydrocarbon group oran alicyclic hydrocarbon group, a C₁ to C₁₈ aliphatic hydrocarbon groupor a C₃ to C₁₈ alicyclic hydrocarbon group is preferred.

Examples of the aromatic hydrocarbon group where a hydrogen atom may bereplaced by an alkoxy group include a p-methoxyphenyl group.

Examples of the aliphatic hydrocarbon group where a hydrogen atom may bereplaced by an aromatic hydrocarbon group include an aralkyl group suchas benzyl, phenethyl phenylpropyl, trityl, naphthylmethyl andnaphthylethyl groups.

Examples of the alkoxy group include methoxy, ethoxy, propoxy, butoxy,pentyloxy, hexyloxy, heptyloxy, octyloxy, and dodecyloxy groups.

Examples of the acyl group include acetyl, propionyl and butyryl groups.

Examples of the halogen atom include fluorine, chlorine, bromine andiodine atoms.

Examples of the alkylcarbonyloxy group include methylcarbonyloxy,ethylcarbonyloxy, n-propylcarbonyloxy, isopropylcarbonyloxy,n-butylcarbonyloxy, sec-butylcarbonyloxy, tert-butyl carbonyloxy,pentylcarbonyloxy, hexylcarbonyloxy, octylcarbonyloxy and2-ethylhexylcarobonyloxy groups.

The sulfur atom-containing ring which is formed by R^(b4) and R^(b5) maybe a monocyclic or polycyclic group, which may be an aromatic ornon-aromatic group, and which may be a saturated or unsaturated group.The ring is preferably a ring having 3 to 18 carbon atoms, and morepreferably a ring having 4 to 13 carbon atoms. Examples of the sulfuratom-containing ring include a 3- to 12-membered ring, preferably a 3-to 7-membered ring, examples thereof include the following rings.

Examples of the ring formed by R^(b9) and R^(b10) may be any ofmonocyclic, polycyclic, aromatic, non-aromatic, saturated andunsaturated rings. The ring may be a 3- to 12-membered ring, preferablya 3- to 7-membered ring. Examples of the ring include thiolane-1-iumring (tetrahydrothiophenium ring), thian-1-ium ring and1,4-oxathian-4-ium ring.

Examples of the ring formed by R^(b11) and R^(b12) may be any ofmonocyclic, polycyclic, aromatic, non-aromatic, saturated andunsaturated rings. The ring may be a 3- to 12-membered ring, preferablya 3- to 7-membered ring. Examples of the ring include oxocycloheptanering, oxocyclohexane ring, oxonorbornane ring and oxoadamantane ring.

Among the cations represented by the formula (b2-1) to the formula(b2-4), the cation represented by the formula (b2-1) is preferred.

Examples of the cation (b2-1) include the following ones.

Examples of the cation (b2-2) include the following ones.

Examples of the cation (b2-3) include the following ones.

Examples of the cation (b2-4) include the following ones.

Preferred acid generators (B1) are represented by the formula (B1-1) tothe formula (B1-30). Among these, the formulae (B1-1), (B1-2), (B1-3),(B1-5), (B1-6), (B1-7), (B1-11), (B1-12), (B1-13), (B1-14), (B1-17),(B1-20), (B1-21), (B1-23), (B1-24), (B1-25), (B1-26) and (B1-29) whichcontain arylsulfonium cation are preferred.

The proportion of the acid generator (B1) is preferably 30% by mass ormore, and 100% by mass or less, more preferably 50% by mass or more, and100% by mass or less, and still more preferably substantially 100% byweight with respect to 100% by mass of total acid generator (B).

In the resist composition of the disclosure, the proportion of the acidgenerator (B) is preferably 1 parts by mass or more and more preferably3 parts by mass or more, and preferably 30 parts by mass or less andmore preferably 25 parts by mass or less with respect to 100 parts bymass of the resin (A1).

In the resist composition of the disclosure, the acid generator (B) maybe used as a single salt or as a combination of two or more of salts.

<Solvent (E)>

The proportion of a solvent (E) is generally 90% by mass or more,preferably 92% by mass or more, and more preferably 94% by mass or more,and also preferably 99% by mass or less, and more preferably 99.9% bymass or less. The proportion of the solvent (E) can be measured with aknown analytical method such as liquid chromatography and gaschromatography.

Examples of the solvent (E) include glycol ether esters such asethylcellosolve acetate, methylcellosolve acetate andpropyleneglycolmonomethylether acetate; glycol ethers such aspropyleneglycolmonomethylether; esters such as ethyl lactate, butylacetate, amyl acetate and ethyl pyruvate; ketones such as acetone,methyl isobutyl ketone, 2-heptanone and cyclohexanone; and cyclic esterssuch as γ-butyrolactone. These solvents may be used as a single solventor as a mixture of two or more solvents.

<Quencher (C)>

The resist composition of the disclosure may include a quencher such asa basic nitrogen-containing organic compound and a salt which generatesan acid weaker in acidity than an acid generated from the acidgenerator.

The proportion of the quencher is preferably 0.01% by mass to 5% by masswith respect to the total solid components of the resist composition.

Examples of the basic nitrogen-containing organic compound include anamine and ammonium salts. The amine may be an aliphatic amine or anaromatic amine. The aliphatic amine includes any of a primary amine,secondary amine and tertiary amine.

Specific examples of the amine include 1-naphtylamine, 2-naphtylamine,aniline, diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine,heptylamine, octylamine, nonylamine, decylamine, dibutylamine,dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine,didecylamine, triethylamine, trimethylamine, tripropylamine,tributylamine, tripentylamine, trihexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, methyldibutylamine,methyldipentylamine, methyldihexylamine, methyldicyclohexylamine,methyldiheptylamine, methyldioctylamine, methyldinonylamine,methyldidecylamine, ethyldibutylamine, ethyldipentylamine,ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine,ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine,tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine, ethylenediamine, tetramethylene diamine, hexamethylene diamine,4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenylmethane, 2,2′-methylenebisaniline,imidazole, 4-methylimidazole, pyridine, 4-methylpyridine,1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene,1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane,di(2-pyridyl)ketone, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide,2,2′-dipyridylamine, 2,2′-dipicolylamine and bipyridine. Among these,diisopropylaniline is preferred, particularly 2,6-diisopropylaniline ismore preferred.

Specific examples of the ammonium salt include tetramethylammoniumhydroxide, tetraisopropylammonium hydroxide, tetrabutylammoniumhydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,phenyltrimethyl ammonium hydroxide,3-(trifluoromethyl)phenyltrimethylammonium hydroxide, tetra-n-butylammonium salicylate and choline.

<Weak Acid Salt>

The salt generating an acid which is lower in acidity than an acidgenerated from the acid generator (B) is sometimes referred to as “weakacid salt”. The “acidity” can be represented by acid dissociationconstant, pKa, of an acid generated from a weak acid salt. Examples ofthe weak acid salt include a salt generating an acid of pKa representsgenerally more than −3, preferably −1 to 7, and more preferably 0 to 5.

Specific examples of the weak acid salt include the following salts, thesalt of formula (D), and salts as disclosed in JP2012-229206A1,JP2012-6908A1, JP2012-72109A1, JP2011-39502A1 and JP2011-191745A1,preferably the salt of formula (D).

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlyrepresent a C₁ to C₁₂ hydrocarbon group, a C₁ to C₆ alkoxyl group, a C₂to C₇ acyl group, a C₂ to C₇ acyloxy group, a C₂ to C₇ alkoxycarbonylgroup, a nitro group or a halogen atom;

m′ and n′ each independently represent an integer of 0 to 4.

Examples of the hydrocarbon group of R^(D1) and R^(D2) include any of analiphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatichydrocarbon group and a combination thereof.

Examples of the aliphatic hydrocarbon group include an alkyl group suchas methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl,pentyl, hexyl and nonyl groups.

The alicyclic hydrocarbon group is any one of monocyclic or polycyclichydrocarbon group, and saturated or unsaturated hydrocarbon group.Examples thereof include a cycloalkyl group such as cyclopropyl,cyclobutyl, cyclopentyl, cyclohexyl, cyclononyl and cyclododecyl groups;adamantyl and norbornyl groups. The alicyclic hydrocarbon group ispreferably saturated hydrocarbon group.

Examples of the aromatic hydrocarbon group include an aryl group such asphenyl, 1-naphthyl, 2-naphthyl, 2-methylphenyl, 3-methylphenyl,4-methylphenyl, 4-ethylphenyl, 4-propylphenyl, 4-isopropylphenyl,4-butylphenyl, 4-tert-butylphenyl, 4-hexylphenyl, 4-cyclohexylphenyl,anthryl, p-adamantylphenyl, tolyl, xylyl, cumenyl, mesityl, biphenyl,phenanthryl, 2,6-diethylphenyl and 2-methyl-6-ethylphenyl groups.

Examples of the combination thereof include an alkyl-cycloalkyl, acycloalkyl-alkyl, aralkyl (e.g., phenylmethyl, 1-phenylethyl,2-phenylethyl, 1-phenyl-1-propyl, 1-phenyl-2-propyl, 2-phenyl-2-propyl,3-phenyl-1-propyl, 4-phenyl-1-butyl, 5-phenyl-1-pentyl and6-phenyl-1-hexyl groups) groups.

Examples of the alkoxyl group include methoxy and ethoxy groups.

Examples of the acyl group include acetyl, propanonyl, benzoyl andcyclohexanecarbonyl groups.

Examples of the acyloxy group include a group in which oxy group (—O—)bonds to an acyl group.

Examples of the alkoxycarbonyl group include a group in which thecarbonyl group (—CO—) bonds to the alkoxy group.

Example of the halogen atom is a chlorine atom, a fluorine atom andbromine atom.

In the formula (D), R^(D1) and R^(D2) in each occurrence independentlypreferably represent a C₁ to C₈ alkyl group, a C₃ to C₁₀ cycloalkylgroup, a C₁ to C₆ alkoxyl group, a C₂ to C₄ acyl group, a C₂ to C₄acyloxy group, a C₂ to C₄ alkoxycarbonyl group, a nitro group or ahalogen atom.

m′ and n′ independently preferably represent an integer of 0 to 3, morepreferably an integer of 0 to 2, and more preferably 0.

Specific examples of the salt of the formula (D) include compoundsbelow.

The salt of the formula (D) can be produced by a method described in“Tetrahedron Vol. 45, No. 19, p6281-6296”. Also, commercially availablecompounds can be used as the salt of the formula (D).

In the resist composition of the disclosure, the proportion of the saltwhich generates an acid weaker in acidity than an acid generated fromthe acid generator, for example, the salt of the formula (D) ispreferably 0.01% by mass to 5% by mass, more preferably 0.01% by mass to4% by mass, and still more preferably 0.01% by mass to 3% by mass withrespect to total solid components of the resist composition.

<Other Ingredient>

The resist composition can also include other ingredient (which issometimes referred to as “other ingredient (F)”). Examples of the otheringredient (F) include various additives such as sensitizers,dissolution inhibitors, surfactants, stabilizers, and dyes, as needed.

<Preparing the Resist Composition>

The present resist composition can be prepared by mixing the resins (A1)and (A2), the acid generator (B), the resin other than the resin (A),the quencher, the solvent (E) and the other ingredient (F), as needed.There is no particular limitation on the order of mixing. The mixing maybe performed in an arbitrary order. The temperature of mixing may beadjusted to an appropriate temperature within the range of 10 to 40° C.,depending on the kinds of the resin and solubility in the solvent (E) ofthe resin. The time of mixing may be adjusted to an appropriate timewithin the range of 0.5 to 24 hours, depending on the mixingtemperature. There is no particular limitation to the tool for mixing.An agitation mixing may be used.

After mixing the above ingredients, the present resist compositions canbe prepared by filtering the mixture through a filter having about 0.003to 0.2 μm pore diameter.

<Method for Producing Resist Pattern>

The method for producing a resist pattern of the disclosure includes thesteps of:

(1) applying the resist composition of the disclosure onto a substrate;

(2) drying the applied composition to form a composition layer;

(3) exposing the composition layer;

(4) heating the exposed composition layer, and

(5) developing the heated composition layer.

Applying the resist composition onto the substrate can generally becarried out through the use of a resist application device, such as aspin coater known in the field of semiconductor microfabricationtechnique. Examples of the substrate include inorganic substrates suchas silicon wafer. The substrate may be washed, and an organicantireflection film may be formed on the substrate by use of acommercially available antireflection composition, before theapplication of the resist composition.

The solvent evaporates from the resist composition and a compositionlayer with the solvent removed is formed. Drying the applied compositionlayer, for example, can be carried out using a heating device such as ahotplate (so-called “prebake”), a decompression device, or a combinationthereof. The temperature is preferably within the range of 50 to 200° C.The time for heating is preferably 10 to 180 seconds. The pressure ispreferably within the range of 1 to 1.0×10⁵ Pa.

The obtained composition layer is generally exposed using an exposureapparatus or a liquid immersion exposure apparatus. The exposure isgenerally carried out using with various types of exposure light source,such as irradiation with ultraviolet lasers, i.e., KrF excimer laser(wavelength: 248 nm), ArF excimer laser (wavelength: 193 nm), F₂ excimerlaser (wavelength: 157 nm), irradiation with harmonic laser light offar-ultraviolet or vacuum ultra violet wavelength-converted laser lightfrom a solid-state laser source (YAG or semiconductor laser or thelike), or irradiation with electron beam or EUV or the like. In thespecification, such exposure to radiation is sometimes referred to becollectively called as exposure. The exposure is generally carried outthrough a mask that corresponds to the desired pattern. When electronbeam is used as the exposure light source, direct writing without usinga mask can be carried out.

After exposure, the composition layer is subjected to a heat treatment(so-called “post-exposure bake”) to promote the deprotection reaction.The heat treatment can be carried out using a heating device such as ahotplate. The heating temperature is generally in the range of 50 to200° C., preferably in the range of 70 to 150° C.

The developing of the baked composition film is usually carried out witha developer using a development apparatus. Developing can be conductedin the manner of dipping method, paddle method, spray method and dynamicdispensing method. Temperature for developing is generally 5 to 60° C.The time for developing is preferably 5 to 300 seconds.

The photoresist pattern obtained from the photoresist composition may bea positive one or a negative one by selecting suitable developer.

The development for obtaining a positive photoresist pattern is usuallycarried out with an alkaline developer. The alkaline developer to beused may be any one of various alkaline aqueous solution used in theart. Generally, an aqueous solution of tetramethylammonium hydroxide or(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as“choline”) is often used. The surfactant may be contained in thealkaline developer.

After development, the resist pattern formed is preferably washed withultrapure water, and the residual water remained on the resist film oron the substrate is preferably removed therefrom.

The development for obtaining a negative photoresist pattern is usuallycarried out with a developer containing an organic solvent. The organicsolvent to be used may be any one of various organic solvents used inthe art, examples of which include ketone solvents such as 2-hexanone,2-heptanone; glycol ether ester solvents such aspropyleneglycolmonomethylether acetate; ester solvents such as the butylacetate; glycol ether solvents such as thepropyleneglycolmonomethylether; amide solvents such asN,N-dimethylacetamide; aromatic hydrocarbon solvents such as anisole.

In the developer containing an organic solvent, the amount of organicsolvents is preferably 90% by mass to 100% by mass, more preferably 95%by mass to 100% by mass of the developer. The developer still morepreferably consists essentially of organic solvents.

Among these, the developer containing an organic solvent preferablycontains butyl acetate and/or 2-heptanone. In the developer containingan organic solvent, the total amount of butyl acetate and 2-heptanone ispreferably 50% by mass to 100% by mass of the developer, more preferably90% by mass to 100% by mass of the developer. The developer still morepreferably consists essentially of butyl acetate and/or 2-heptanone.

Developers containing an organic solvent may contain a surfactant. Also,the developer containing an organic solvent may include a little water.

The developing with a developer containing an organic solvent can befinished by replacing the developer by another solvent.

After development, the photoresist pattern formed is preferably washedwith a rinse agent. Such rinse agent is not unlimited provided that itdoes not detract a photoresist pattern. Examples of the agent includesolvents which contain organic solvents other than the above-mentioneddevelopers, such as alcohol agents or ester agents.

After washing, the residual rinse agent remained on the substrate orphotoresist film is preferably removed therefrom.

<Application>

The resist composition of the disclosure is useful for excimer laserlithography such as ArF, KrF, electron beam (EB) exposure lithography orextreme-ultraviolet (EUV) exposure lithography, and is more useful forArF excimer laser exposure lithography.

The resist composition of the disclosure can be used in semiconductormicrofabrication.

EXAMPLES

The disclosure will be described more specifically by way of examples,which are not construed to limit the scope of the disclosure.

All percentages and parts expressing the content or amounts used in theExamples and Comparative Examples are based on mass, unless otherwisespecified.

The weight average molecular weight is a value determined by gelpermeation chromatography.

Column: TSK gel Multipore HXL-M×3+guardcolumn (Tosoh Co. Ltd.)

Eluant: tetrahydrofuran

Flow rate: 1.0 mL/min

Detecting device: RI detector

Column temperature: 40° C.

Injection amount: 100 μL

Standard material for calculating molecular weight: standard polystyrene(Tosoh Co. ltd.)

Structures of compounds were determined by mass spectrometry (LiquidChromatography: 1100 Type, manufactured by AGILENT TECHNOLOGIES LTD.,Mass Spectrometry: LC/MSD Type, manufactured by AGILENT TECHNOLOGIESLTD.). The value of the peak in the mass spectrometry is referred to as“MASS”.

Synthesis Example 1 Synthesis of the Salt Represented by the Formula(B1-5)

Into a reactor, 50.49 parts of compound represented by the formula(B1-5-a) and 252.44 parts of chloroform were charged and stirred at 23°C. for 30 minutes. Then 16.27 parts of compound represented by theformula (B1-5-b) were dropped thereinto and the obtained mixture wasstirred at 23° C. for one hour to obtain a solution containing a saltrepresented by the formula (B1-5-c). To the obtained solution, 48.80parts of a salt represented by the formula (B1-5-d) and 84.15 parts ofion-exchanged water were added and the obtained mixture was stirred at23° C. for 12 hours. From the obtained solution which had two layers,the chloroform layer was collected and then 84.15 parts of ion-exchangedwater were added thereto for washing. The washing with water step wasconducted five times. To the washed chloroform layer, 3.88 parts ofactive carbon was added and the obtained mixture was stirred, followedby filtrating. The collected filtrate was concentrated and then 125.87parts of acetonitrile were added thereto and the obtained mixture wasstirred, followed by being concentrated. 20.62 parts of acetonitrile and309.30 parts of tert-butyl methyl ether were added to the obtainedresidues, followed by being stirred at 23° C. for about 30 minutes. Thenthe supernatant was removed therefrom, and the residues wereconcentrated. To the concentrated residues, 200 parts of n-heptane wereadded and the obtained mixture was stirred at 23° C. for about 30minutes, followed by being filtrated whereby giving 61.54 parts of thesalt represented by the formula (B1-5).

MASS(ESI(+)Spectrum):M+ 375.2

MASS(ESI(−)Spectrum):M− 339.1

Synthesis Example 2 Synthesis of the Salt Represented by the Formula(B1-21)

The compound represented by the formula (B1-21-b) was produced accordingto a method recited in JP2008-209917A1.

Into a reactor, 30.00 parts of compound represented by the formula(B1-21-b) and 35.50 parts of salt represented by the formula (B1-21-a),100 parts of chloroform and 50 parts of ion exchanged water were chargedand stirred at 23° C. for about 15 hours. The obtained reaction mixture,which had two layers, was separated into a chloroform layer therefrom.To the chloroform layer, 30 parts of ion exchanged water was added andwashed with it. These steps were conducted five times. Then the washedlayer was concentrated, and then, 100 parts of tert-butyl methyl etherwas added to the obtained residues and the obtained mixture was stirredat 23° C. for about 30 minutes. The resulting mixture was filtrated toobtain 48.57 parts of salt represented by the formula (B1-21-c).

Into a reactor, 20.00 parts of salt represented by the formula(B1-21-c), 2.84 parts of compound represented by the formula (B1-21-d)and 250 parts of monochlorobenzene were charged and stirred at 23° C.for 30 minutes. To the resulting mixture, 0.21 parts of copper (II)dibenzoate was added and the obtained mixture was stirred at 100° C. for1 hour. The reaction mixture was concentrated, and then, 200 parts ofchloroform and 50 parts of ion exchanged water were added to theobtained residues and the obtained mixture was stirred at 23° C. for 30minutes, followed by separating an organic layer to wash with water. 50parts of ion exchanged water was added to the obtained organic layer,and the obtained mixture was stirred at 23° C. for 30 minutes, followedby separating an organic layer. The washing step with water wasconducted five times. The obtained organic layer was concentrated, andthen the obtained residues were dissolved in 53.51 parts ofacetonitrile. Then the mixture was concentrated, and then 113.05 partsof tert-butyl methyl ether was added thereto and the obtained mixturewas stirred, followed by filtrating it to obtain 10.47 parts of the saltrepresented by the formula (B1-21).

MASS(ESI(+)Spectrum):M+ 237.1

MASS(ESI(−)Spectrum):M− 339.1

Synthesis Example 3 Synthesis of the Salt Represented by the Formula(B1-22)

Into a reactor, 11.26 parts of salt represented by the formula(B1-21-a), 10 parts of compound represented by the formula (B1-22-b), 50parts of chloroform and 25 parts of ion exchanged water were charged andstirred at 23° C. for about 15 hours. The obtained reaction mixture,which had two layers, was separated into a chloroform layer therefrom.To the chloroform layer, 15 parts of ion exchanged water were added andwashed with it: These steps were conducted five times. Then the washedlayer was concentrated, and then 50 parts of tert-butyl methyl ether wasadded to the obtained residues, and the obtained mixture was stirred at23° C. for about 30 minutes. The resulting mixture was filtrated toobtain 11.75 parts of the salt represented by the formula (B1-22-c).

Into a reactor, 11.71 parts of a salt represented by the formula(B1-22-c), 1.70 parts of a compound represented by the formula (B1-21-d)and 46.84 parts of monochlorobenzene were charged and stirred at 23° C.for 30 minutes. To the resulting mixture, 0.12 parts of copper (II)dibenzoate was added and the obtained mixture was stirred at 100° C. for30 minutes. The reaction mixture was concentrated, and then 50 parts ofchloroform and 12.50 parts of ion exchanged water were added to theobtained residues, and the obtained mixture was stirred at 23° C. for 30minutes, followed by separating an organic layer to wash with water.12.50 parts of ion exchanged water was added to the obtained organiclayer and the obtained mixture was stirred at 23° C. for 30 minutes,followed by separating an organic layer to wash with water. The washingstep with water was conducted eight times. Then the obtained organiclayer was concentrated, and then 50 parts of tert-butyl methyl etherwere added thereto and the obtained mixture was stirred, followed byfiltrating it to obtain 6.84 parts of the salt represented by theformula (B1-22).

MASS(ESI(+)Spectrum):M+ 237.1

MASS(ESI(−)Spectrum):M− 323.0

Synthesis Examples of Resins

The monomers used for Synthesis Examples of the resins are shown below.These monomers are referred to as “monomer (X)” where “(X)” is thesymbol of the formula representing the structure of each monomer.

Example 1 Synthesis of Resin A1-1

Monomer (a4-0-1), monomer (I-2) and monomer (a6-2) were mixed togetherwith the mole ratio of monomer (a4-0-1), monomer (I-2) and monomer(a6-2)=50:35:15, and propylene glycol monomethyl ether acetate was addedthereto in the amount equal to 1.2 times by mass of the total amount ofmonomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.85% by mole and 2.55% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactionmixture was poured into a large amount of a mixture of methanol and ionexchanged water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was poured into another methanol to wash.The obtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 13000 in 75% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A1-1.

Example 2 Synthesis of Resin A1-2

Monomer (a4-0-12), monomer (I-1) and monomer (a6-2) were mixed togetherwith the mole ratio of monomer (a4-0-12), monomer (I-1) and monomer(a6-2)=50:45:5, and propylene glycol monomethyl ether acetate was addedthereto in the amount equal to 1.2 times by mass of the total amount ofmonomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.85% by mole and 2.55% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactionmixture was poured into a large amount of a mixture of methanol and ionexchanged water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was poured into another methanol to wash.The obtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 13000 in 73% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A1-2.

Example 3 Synthesis of Resin A1-3

Monomer (a4-0-12), monomer (I-1) and monomer (a6-1) were mixed togetherwith the mole ratio of monomer (a4-0-12), monomer (I-1) and monomer(a6-1)=50:45:5, and propylene glycol monomethyl ether acetate was addedthereto in the amount equal to 1.2 times by mass of the total amount ofmonomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 0.85% by mole and 2.55% by mole respectivelywith respect to the total amount of monomers, and the resultant mixturewas heated for about 5 hours at 75° C. Then, the obtained reactionmixture was poured into a large amount of a mixture of methanol and ionexchanged water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was poured into another methanol to wash.The obtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 12000 in 70% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A1-3.

Example 4 Synthesis of Resin A1-4

Monomer (a4-0-12) and monomer (a6-2) were mixed together with the moleratio of monomer (a4-0-12) and monomer (a6-2)=70:30, and propyleneglycol monomethyl ether acetate was added thereto in the amount equal to1.2 times by mass of the total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.9% by mole and 2.7% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. Then, theobtained reaction mixture was poured into a large amount of a mixture ofmethanol and ion exchanged water to precipitate a resin. The obtainedresin was filtrated. The obtained resin was poured into another methanolto wash. The obtained resin was filtrated to obtain the copolymer havinga weight average molecular weight of about 13000 in 70% yield. Thisresin, which had the structural units of the following formulae, wasreferred to Resin A1-4.

Example 5 Synthesis of Resin A1-5

Monomer (a4-0-12), monomer (I-1) and monomer (a6-2) were mixed togetherwith the mole ratio of monomer (a4-0-12), monomer (I-1) and monomer(a6-2)=50:45:5, and propylene glycol monomethyl ether acetate was addedthereto in the amount equal to 1.2 times by mass of the total amount ofmonomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and ionexchanged water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was poured into another methanol to wash.The obtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 8200 in 78% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A1-5.

Example 6 Synthesis of Resin A1-6

Monomer (a4-0-12), monomer (I-1) and monomer (a6-1) were mixed togetherwith the mole ratio of monomer (a4-0-12), monomer (I-1) and monomer(a6-1)=50:45:5, and propylene glycol monomethyl ether acetate was addedthereto in the amount equal to 1.2 times by mass of the total amount ofmonomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and ionexchanged water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was poured into another methanol to wash.The obtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 8800 in 74% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A1-6.

Example 7 Synthesis of Resin A1-7

Monomer (a4-0-12), monomer (I-1) and monomer (a6-3) were mixed togetherwith the mole ratio of monomer (a4-0-12), monomer (I-1) and monomer(a6-3)=50:45:5, and propylene glycol monomethyl ether acetate was addedthereto in the amount equal to 1.2 times by mass of the total amount ofmonomers to obtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 75° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and ionexchanged water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was poured into another methanol to wash.The obtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 7900 in 69% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A1-7.

Synthesis Example 4 Synthesis of Resin A2-1

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-3) and monomer(a3-4-2) were mixed together with a mole ratio of monomer (a1-1-3),monomer (a1-2-9), monomer (a2-1-3) and monomer (a3-4-2)=45:14:2.5:38.5,and propylene glycol monomethyl ether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. The obtainedresin was dissolved in another propylene glycol monomethyl ether acetateto obtain a solution, and the solution was poured into a large amount ofa mixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thecopolymer having a weight average molecular weight of about 7600 in 68%yield. This resin, which had the structural units of the followingformulae, was referred to Resin A2-1.

Synthesis Example 5 Synthesis of Resin A2-2

Monomer (a1-1-3), monomer (a1-2-7), monomer (a2-1-1), monomer (a3-1-1)and monomer (a6-2) were mixed together with a mole ratio of monomer(a1-1-3), monomer (a1-2-7), monomer (a2-1-1), monomer (a3-1-1) andmonomer (a6-2)=24:11:6:38:21, and propylene glycol monomethyl etheracetate was added thereto in the amount equal to 1.5 times by mass ofthe total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 1% by mole and 3% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 73° C. Then, theobtained reaction mixture was poured into a large amount of a mixture ofmethanol and water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was dissolved in another propylene glycolmonomethyl ether acetate to obtain a solution, and the solution waspoured into a large amount of a mixture of methanol and water toprecipitate the resin. The obtained resin was filtrated. Theseoperations were repeated twice to obtain the copolymer having a weightaverage molecular weight of about 7500 in 62% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A2-2.

Synthesis Example 6 Synthesis of Resin A2-3

Monomer (a1-1-3), monomer (a1-2-9), monomer (a2-1-1) and monomer(a3-4-2) were mixed together with a mole ratio of monomer (a1-1-3),monomer (a1-2-9), monomer (a2-1-1) and monomer (a3-4-2)=45:14:2.5:38.5,and propylene glycol monomethyl ether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. The obtainedresin was dissolved in another propylene glycol monomethyl ether acetateto obtain a solution, and the solution was poured into a large amount ofa mixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thecopolymer having a weight average molecular weight of about 7900 in 67%yield. This resin, which had the structural units of the followingformulae, was referred to Resin A2-3.

Synthesis Example 7 Synthesis of Resin A1X-1

Monomer (a4-0-1) and monomer (I-2) were mixed together with a mole ratioof monomer (a4-0-1) and monomer (I-2)=50:50, and propylene glycolmonomethyl ether acetate was added thereto in the amount equal to 1.2times by mass of the total amount of monomers to obtain a solution.Azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) were addedas initiators to the solution in the amounts of 0.9% by mole and 2.7% bymole respectively with respect to the total amount of monomers, and theresultant mixture was heated for about 5 hours at 75° C. The obtainedreaction mixture was poured into a large amount of a mixture of methanoland ion exchanged water to precipitate a resin. The obtained resin wasfiltrated. The obtained resin was poured into another methanol to wash.The obtained resin was filtrated to obtain the copolymer having a weightaverage molecular weight of about 12000 in 90% yield. This resin, whichhad the structural units of the following formulae, was referred toResin A1X-1.

Synthesis Example 8 Synthesis of Resin A1X-2

Monomer (a1-1-3), monomer (a1-2-7), monomer (a2-1-1), monomer (a3-1-1),monomer (a6-2) and monomer (a4-2-3) were mixed together with the moleratio of monomer (a1-1-3), monomer (a1-2-7), monomer (a2-1-1), monomer(a3-1-1), monomer (a6-2) and monomer (a4-2-3)=24:11:6:28:21:10 andpropylene glycol monomethyl ether acetate was added thereto in theamount equal to 1.5 times by mass of the total amount of monomers toobtain a solution. Azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) were added as initiators to thesolution in the amounts of 1% by mole and 3% by mole respectively withrespect to the total amount of monomers, and the resultant mixture washeated for about 5 hours at 73° C. Then, the obtained reaction mixturewas poured into a large amount of a mixture of methanol and water toprecipitate a resin. The obtained resin was filtrated. The obtainedresin was dissolved in another propylene glycol monomethyl ether acetateto obtain a solution, and the solution was poured into a large amount ofa mixture of methanol and water to precipitate the resin. The obtainedresin was filtrated. These operations were repeated twice to obtain thecopolymer having a weight average molecular weight of about 7600 in 58%yield. This resin, which had the structural units of the followingformulae, was referred to Resin A1X-2.

(Preparing Resist Compositions)

Resist compositions were prepared by mixing and dissolving each of thecomponents shown in Table 1, and then filtrating through a fluororesinfilter having 0.2 μm pore diameter. The obtained resist compositionswere stored for 3 weeks at 30° C. Then, the properties of the resistcompositions were evaluated.

TABLE 1 Weakly Acidic Acid Inner PB/PEB Resin Generator (B) Salt (D) (°C./ Resist Comp. (parts) (parts) (parts) ° C.) Composition 1 A1-1/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 2 A1-1/A2-1 =B1-5/B1-22 = D1 = 0.28 90/85 0.7/10 0.4/0.4 Composition 3 A1-2/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 4 A1-3/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 5 A1-4/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 6 A1-2/A2-2 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 7 A1-5/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 8 A1-6/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 9 A1-7/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 10 A1-5/A2-3 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 11 A1-6/A2-3 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Composition 12 A1-7/A2-3 =B1-21/B1-22 = D1 = 0.28 90/85 0.7/10 0.9/0.4 Comparative A1X-1/A2-1 =B1-21/B1-22 = D1 = 0.28 90/85 Comp. 1 0.7/10 0.9/0.4 ComparativeA1X-2/A2-2 = B1-21/B1-22 = D1 = 0.28 90/85 Comp. 2 0.7/10 0.9/0.4Comparative A1X-2 = 10 B1-21/B1-22 = D1 = 0.28 90/85 Comp. 3 0.9/0.4

<Resin>

Resins: Resins A1-1 to A1-7, A2-1 to A2-3, A1X-1 and A1X-2, eachprepared by the method as described above.

<Acid Generator (B)>

B1-5: Salt represented by the formula (B1-5)

B1-21: Salt represented by the formula (B1-21)

B1-22: Salt represented by the formula (B1-22)

<Weakly Acidic Inner Salt (D)>

D1: Compound as follow, a product of Tokyo Chemical Industry Co., LTD

<Solvent for Resist compositions> Propyleneglycol monomethyl etheracetate 265 parts  Propyleneglycol monomethyl ether 20 parts 2-Heptanone20 parts γ-butyrolactone 3.5 parts 

<Evaluation of Resist Compositions>

A composition for an organic antireflective film (“ARC-29”, by NissanChemical Co. Ltd.) was applied onto 12-inch silicon wafer and baked for60 seconds at 205° C. to form a 78 nm thick organic antireflective film.

One of the resist compositions was then applied thereon by spin coatingin such a manner that the thickness of the film after drying(pre-baking) became 85 nm.

The obtained wafer was then pre-baked for 60 sec on a direct hot plateat the temperature given in the “PB” column in Table 1.

On the wafers on which the resist film had thus been formed, the filmwas then exposed through a mask for forming trench patterns (pitch 120nm/trench width 40 nm) with changing exposure quantity stepwise, by anArF excimer laser stepper for liquid-immersion lithography (“XT:1900Gi”by ASML Ltd.: NA=1.35, Annular σout=0.9 σ sin=0.7 XY-pol.). Ultrapurewater was used for medium of liquid-immersion.

After the exposure, post-exposure baking was carried out for 60 secondsat the temperature given in the “PEB” column in Table 1.

Then, development was carried out with butyl acetate (a product of TokyoChemical Industry Co., LTD) at 23° C. for 20 seconds in the manner ofdynamic dispensing method to obtain negative resist patterns.

Effective sensitivity was represented as the exposure quantity at whichthe resist pattern with 40 nm trench width was obtained.

<Focus Margin (DOF) Evaluation>

Negative resist patterns were produced in the same manner as describedabove, except that the exposure was conducted with changing the distancefrom the source of exposure stepwise, and the exposure quantity was keptat what is equivalent to the effective sensitivity at the beginning ofit. DOF (nm) is represented by the focus range, i.e. the maximumdifference among the distances in which the width of the trench patternis 40 nm±5% (38 to 42 nm).

Table 2 illustrates the results thereof.

(Evaluation of Defects)

Negative resist patterns were produced in the same manner as describedabove, except that the film was exposed with exposure quantity at whichthe ratio of the widths between the line and the space became 1:1, usingan ArF excimer laser stepper for immersion lithography (“XT:1900Gi” byASML Ltd.: NA=1.35, Annular σ_(out)=0.85 σ_(in)=0.65 XY-pol.) and a maskfor making a 1:1 line and space patterns (pitch 80 nm, line width 40nm).

Thereafter, the number of defects was counted using a defect inspectionapparatus (KLA-2360, KLA-Tencor Co. Ltd.). Table 2 illustrates theresults thereof.

TABLE 2 Resist Composition DOF (nm) Defects Ex. 8 Composition 1 120 360Ex. 9 Composition 2 120 350 Ex. 10 Composition 3 120 320 Ex. 11Composition 4 120 390 Ex. 12 Composition 5 105 420 Ex. 13 Composition 6105 370 Ex. 14 Composition 7 135 340 Ex. 15 Composition 8 105 330 Ex. 16Composition 9 120 320 Ex. 17 Composition 10 150 320 Ex. 18 Composition11 105 340 Ex. 19 Composition 12 135 300 Comparative Ex. 1 ComparativeComp. 1 90 980 Comparative Ex. 2 Comparative Comp. 2 90 15600Comparative Ex. 3 Comparative Comp. 3 75 16800

The resin of the disclosure is useful for resist compositions. Theresist composition including the resin can show excellent preservationstability, and provide resist patterns with satisfactory wide focusmargin (DOF) and reduced defects even after storage for a certainperiod. The resist composition is useful for semiconductor microfabrication.

1. A resist composition comprising (A1) a resin which comprises astructural unit represented by formula (a4):

wherein R³ represents a hydrogen atom or a methyl group, and R⁴represents a C₁ to C₂₄ saturated hydrocarbon group having a fluorineatom, and a methylene group contained in the saturated hydrocarbon groupmay be replaced by an oxygen atom or a carbonyl group, and a structuralunit having a sulfonyl group, and the resin having no acid-labile group,(A2) a resin having an acid-labile group, and an acid generator.
 2. Theresist composition according to claim 1, wherein the structural unithaving a sulfonyl group is a structural unit having a sultone ring. 3.The resist composition according to claim 2, wherein the sultone ring isa ring represented by formula (T1):

wherein R⁸ represents a C₁ to C₁₂ alkyl group that may have a halogenatom or a hydroxy group, a halogen atom, a hydroxy group, a cyano group,a C₁ to C₁₂ alkoxy group, a C₆ to C₁₂ aryl group, a C₇ to C₁₈ aralkylgroup, a glycidyloxy group, a C₂ to C₁₂ alkoxycarbonyl group or a C₂ toC₄ acyl group, and m represents an integer 0 to
 9. 4. The resistcomposition according to claim 1, wherein the resin (A1) furthercomprises a structural unit represented by formula (I):

wherein R¹ represents a hydrogen atom or a methyl group, L¹ represents asingle bond or a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and R² represents a C₃ to C₁₈ alicyclic hydrocarbon group where ahydrogen atom may be replaced by a C₁ to C₈ aliphatic hydrocarbon groupor a hydroxy group, provided that the carbon atom directly bonded to L¹has no aliphatic hydrocarbon group by which a hydrogen atom has beenreplaced.
 5. The resist composition according to claim 4, wherein R² isan unsubstituted C₃ to C₁₈ alicyclic hydrocarbon group.
 6. The resistcomposition according to claim 1, wherein the structural unitrepresented by the formula (a4) is at least one structural unit selectedfrom the group consisting of a structural unit represented by formula(a4-0), a structural unit represented by formula (a4-1), a structuralunit represented by formula (a4-2) and a structural unit represented byformula (a4-3):

wherein R^(f1) represents a hydrogen atom or a methyl group, and R^(f2)represents a C₁ to C₂₀ saturated hydrocarbon group having a fluorineatom;

wherein R^(f3) represents a hydrogen atom or a methyl group, L³represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and R^(f4) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f5) represents a hydrogen atom or a methyl group, L⁴represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and R^(f6) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f7) represents a hydrogen atom or a methyl group, L⁵represent a C₁ to C₆ alkanediyl group, A^(f13) represents a C₁ to C₁₈divalent saturated hydrocarbon group that may have a fluorine atom,X^(f12) represents an oxycarbonyl group or a carbonyloxy group, andA^(f14) represents a C₁ to C₁₇ saturated hydrocarbon group that may havea fluorine atom, provided that at least one of A^(f13) and A^(f14)represents a saturated hydrocarbon group having a fluorine atom.
 7. Theresist composition according to claim 1, wherein the resin (A2)comprises a structural unit selected from the group consisting of astructural unit represented by formula (a1-1) and a structural unitrepresented by formula (a1-2):

wherein L^(a1) and L^(a2) independently represent —O— or*—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, * represents abinding site to —CO—, R^(a4) and R^(a5) each independently represent ahydrogen atom or a methyl group, R^(ab) and R^(a7) each independentlyrepresent a C₁ to C₈ alkyl group, a C₃ to C₁₈ alicyclic hydrocarbongroup or a combination thereof, m1 represents an integer of 0 to 14, n1represents an integer of 0 to 10, and n1′ represents an integer of 0 to3.
 8. The resist composition according to claim 7, wherein the resin(A2) comprises a structural unit represented by formula (a1-1) and astructural unit represented by formula (a1-2).
 9. A method for producinga resist pattern comprising steps (1) to (5); (1) applying the resistcomposition according to claim 1 onto a substrate; (2) drying theapplied composition to form a composition layer; (3) exposing thecomposition layer; (4) heating the exposed composition layer, and (5)developing the heated composition layer.
 10. A resin comprising astructural unit represented by formula (a4):

wherein R³ represents a hydrogen atom or a methyl group, R⁴ represents aC₁ to C₂₄ saturated hydrocarbon group having a fluorine atom and amethylene group contained in the saturated hydrocarbon group may bereplaced by an oxygen atom or a carbonyl group and a structural unithaving a sulfonyl group, the resin having no acid-labile group.
 11. Theresin according to claim 10, wherein the structural unit having asulfonyl group is a structural unit having a sultone ring.
 12. The resinaccording to claim 11, wherein the sultone ring is a ring represented byformula (T1):

wherein R⁸ represents a C₁ to C₁₂ alkyl group that may have a halogenatom or a hydroxy group, a halogen atom, a hydroxy group, a cyano group,a C₁ to C₁₂ alkoxy group, a C₆ to C₁₂ aryl group, a C₇ to C₁₈ aralkylgroup, a glycidyloxy group, a C₂ to C₁₂ alkoxycarbonyl group or a C₂ toC₄ acyl group, and m represents an integer 0 to
 9. 13. The resinaccording to claim 10, wherein the resin (A1) further comprises astructural unit represented by formula (I):

wherein R¹ represents a hydrogen atom or a methyl group, L¹ represents asingle bond or a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and R² represents a C₃ to C₁₈ alicyclic hydrocarbon group where ahydrogen atom may be replaced by a C₁ to C₈ aliphatic hydrocarbon groupor a hydroxy group, provided that the carbon atom directly bonded to L¹has no aliphatic hydrocarbon group by which a hydrogen atom has beenreplaced.
 14. The resin according to claim 13, wherein R² is anunsubstituted C₃ to C₁₈ alicyclic hydrocarbon group.
 15. The resinaccording to claim 10, wherein the structural unit represented by theformula (a4) is at least one structural unit selected from the groupconsisting of a structural unit represented by formula (a4-0), astructural unit represented by formula (a4-1), a structural unitrepresented by formula (a4-2) and a structural unit represented byformula (a4-3):

wherein R^(f1) represents a hydrogen atom or a methyl group, and R^(f2)represents a C₁ to C₂₀ saturated hydrocarbon group having a fluorineatom;

wherein R^(f3) represents a hydrogen atom or a methyl group, L³represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and R^(f4) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f5) represents a hydrogen atom or a methyl group, L⁴represents a C₁ to C₁₈ divalent saturated hydrocarbon group where amethylene group may be replaced by an oxygen atom or a carbonyl group,and R^(f6) represents a C₁ to C₂₀ saturated hydrocarbon group having afluorine atom;

wherein R^(f7) represents a hydrogen atom or a methyl group, L⁵represent a C₁ to C₆ alkanediyl group, A^(f13) represents a C₁ to C₁₈divalent saturated hydrocarbon group that may have a fluorine atom,X^(f12) represents an oxycarbonyl group or a carbonyloxy group, andA^(f14) represents a C₁ to C₁₇ saturated hydrocarbon group that may havea fluorine atom, provided that at least one of A^(f13) and A^(f14)represents a saturated hydrocarbon group having a fluorine atom.